People in a Beijing district with some 2 million residents were ordered Sunday to undergo mass coronavirus testing following a series of infections as China tightened anti-disease controls ahead of the Winter Olympics.

The government told people in areas of the Chinese capital deemed at high risk for infection not to leave the city after 25 cases were found in the Fengtai district and 14 elsewhere.

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A man puts on his face mask to help protect from the coronavirus as he walks by a decoration for the Beijing Winter Olympics Games at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

People in a Beijing district with some 2 million residents were ordered Sunday to undergo mass coronavirus testing following a series of infections as China tightened anti-disease controls ahead of the Winter Olympics.

People wearing face masks to help protect from the coronavirus line up to get a swab for the COVID-19 test at a hospital in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

On Sunday, Fengtai residents lined up on snow-covered sidewalks in freezing weather for testing.

People wearing face masks to help protect from the coronavirus line up to get a swab for the COVID-19 test at a hospital in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Nationwide, 56 new confirmed infections were reported in the 24 hours through midnight Saturday. The National Health Commission said 37 were believed to have been acquired abroad.

Visitors wearing face masks to help protect from the coronavirus walk by lanterns on display at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Other outbreaks prompted the government to impose travel bans on the major cities of Xi’an and Tianjin.

A man and a child wearing face masks to help protect from the coronavirus walk by a lantern decoration on display outside a mall in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A man and a child wearing face masks to help protect from the coronavirus walk by a lantern decoration on display outside a mall in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Family members wearing face masks to help protect from the coronavirus tour Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Family members wearing face masks to help protect from the coronavirus tour Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Volunteers wearing face masks to help protect from the coronavirus chat each others at an information booth for Beijing Winter Olympics Games at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Volunteers wearing face masks to help protect from the coronavirus chat each others at an information booth for Beijing Winter Olympics Games at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A man and a child wearing face masks to help protect from the coronavirus take a selfie with a decoration for the Beijing Winter Olympics Games in between of the train parked at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A man and a child wearing face masks to help protect from the coronavirus take a selfie with a decoration for the Beijing Winter Olympics Games in between of the train parked at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Visitors wearing face masks to help protect from the coronavirus gather to take souvenir photo with a decoration for the Lunar New Year at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Visitors wearing face masks to help protect from the coronavirus gather to take souvenir photo with a decoration for the Lunar New Year at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Visitors wearing face masks to help protect from the coronavirus gather to take souvenir photo with a decoration for the Beijing Winter Olympics Games on display at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Visitors wearing face masks to help protect from the coronavirus gather to take souvenir photo with a decoration for the Beijing Winter Olympics Games on display at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A child puts on her face mask to help protect from the coronavirus next to a lion dancer decoration at a mall in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A child puts on her face mask to help protect from the coronavirus next to a lion dancer decoration at a mall in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Security personnel wearing face masks to help protect from the coronavirus stand on duty next to a statue on a shopping street in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Security personnel wearing face masks to help protect from the coronavirus stand on duty next to a statue on a shopping street in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A man wearing a face mask to help protect against COVID-19 prepares to eat noodles on the street of Wuhan in central China's Hubei Province, Sunday, Jan. 23, 2022. Sunday will mark two years since the city of Wuhan was placed under a 76-day lockdown as China tried to contain the first major outbreak of the coronavirus pandemic. (AP Photo)

A man wearing a face mask to help protect against COVID-19 prepares to eat noodles on the street of Wuhan in central China's Hubei Province, Sunday, Jan. 23, 2022. Sunday will mark two years since the city of Wuhan was placed under a 76-day lockdown as China tried to contain the first major outbreak of the coronavirus pandemic. (AP Photo)

A resident wearing a face mask to help protect against COVID-19 walks along a narrow street in Wuhan in central China's Hubei Province, Sunday, Jan. 23, 2022. Sunday will mark two years since the city of Wuhan was placed under a 76-day lockdown as China tried to contain the first major outbreak of the coronavirus pandemic. (AP Photo)

A resident wearing a face mask to help protect against COVID-19 walks along a narrow street in Wuhan in central China's Hubei Province, Sunday, Jan. 23, 2022. Sunday will mark two years since the city of Wuhan was placed under a 76-day lockdown as China tried to contain the first major outbreak of the coronavirus pandemic. (AP Photo)

The ruling Communist Party is stepping up enforcement of its “zero tolerance” strategy aimed at isolating every infected person as Beijing prepares to open the Winter Games on Feb. 4 under intensive anti-virus controls.

A man puts on his face mask to help protect from the coronavirus as he walks by a decoration for the Beijing Winter Olympics Games at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A man puts on his face mask to help protect from the coronavirus as he walks by a decoration for the Beijing Winter Olympics Games at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

On Sunday, Fengtai residents lined up on snow-covered sidewalks in freezing weather for testing.

The Chinese capital must “take the most resolute, decisive and strict measures to block the transmission chain of the epidemic,” a city government spokesman, Xu Hejian, told a news conference.

“In principle, personnel in risk areas shall not leave Beijing,” Xu said.

People wearing face masks to help protect from the coronavirus line up to get a swab for the COVID-19 test at a hospital in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

People wearing face masks to help protect from the coronavirus line up to get a swab for the COVID-19 test at a hospital in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Nationwide, 56 new confirmed infections were reported in the 24 hours through midnight Saturday. The National Health Commission said 37 were believed to have been acquired abroad.

China has reported 4,636 deaths out of 105,603 confirmed cases and seven suspected cases since the pandemic began.

The Olympics are being held under strict controls that are meant to isolate athletes, reporters and officials from the outside world. Athletes are required to be vaccinated or undergo a quarantine after arriving in China.

People wearing face masks to help protect from the coronavirus line up to get a swab for the COVID-19 test at a hospital in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

People wearing face masks to help protect from the coronavirus line up to get a swab for the COVID-19 test at a hospital in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Other outbreaks prompted the government to impose travel bans on the major cities of Xi’an and Tianjin.

Visitors wearing face masks to help protect from the coronavirus walk by lanterns on display at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Visitors wearing face masks to help protect from the coronavirus walk by lanterns on display at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A man and a child wearing face masks to help protect from the coronavirus walk by a lantern decoration on display outside a mall in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A man and a child wearing face masks to help protect from the coronavirus walk by a lantern decoration on display outside a mall in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Family members wearing face masks to help protect from the coronavirus tour Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Family members wearing face masks to help protect from the coronavirus tour Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Volunteers wearing face masks to help protect from the coronavirus chat each others at an information booth for Beijing Winter Olympics Games at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Volunteers wearing face masks to help protect from the coronavirus chat each others at an information booth for Beijing Winter Olympics Games at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A man and a child wearing face masks to help protect from the coronavirus take a selfie with a decoration for the Beijing Winter Olympics Games in between of the train parked at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A man and a child wearing face masks to help protect from the coronavirus take a selfie with a decoration for the Beijing Winter Olympics Games in between of the train parked at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Visitors wearing face masks to help protect from the coronavirus gather to take souvenir photo with a decoration for the Lunar New Year at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Visitors wearing face masks to help protect from the coronavirus gather to take souvenir photo with a decoration for the Lunar New Year at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Visitors wearing face masks to help protect from the coronavirus gather to take souvenir photo with a decoration for the Beijing Winter Olympics Games on display at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Visitors wearing face masks to help protect from the coronavirus gather to take souvenir photo with a decoration for the Beijing Winter Olympics Games on display at Qianmen Street, a popular tourist spot in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A child puts on her face mask to help protect from the coronavirus next to a lion dancer decoration at a mall in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A child puts on her face mask to help protect from the coronavirus next to a lion dancer decoration at a mall in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Security personnel wearing face masks to help protect from the coronavirus stand on duty next to a statue on a shopping street in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

Security personnel wearing face masks to help protect from the coronavirus stand on duty next to a statue on a shopping street in Beijing, Sunday, Jan. 23, 2022. Chinese authorities have called on the public to stay where they are during the Lunar New Year instead of traveling to their hometowns for the year's most important family holiday. (AP PhotoAndy Wong)

A man wearing a face mask to help protect against COVID-19 prepares to eat noodles on the street of Wuhan in central China's Hubei Province, Sunday, Jan. 23, 2022. Sunday will mark two years since the city of Wuhan was placed under a 76-day lockdown as China tried to contain the first major outbreak of the coronavirus pandemic. (AP Photo)

A man wearing a face mask to help protect against COVID-19 prepares to eat noodles on the street of Wuhan in central China's Hubei Province, Sunday, Jan. 23, 2022. Sunday will mark two years since the city of Wuhan was placed under a 76-day lockdown as China tried to contain the first major outbreak of the coronavirus pandemic. (AP Photo)

A resident wearing a face mask to help protect against COVID-19 walks along a narrow street in Wuhan in central China's Hubei Province, Sunday, Jan. 23, 2022. Sunday will mark two years since the city of Wuhan was placed under a 76-day lockdown as China tried to contain the first major outbreak of the coronavirus pandemic. (AP Photo)

A resident wearing a face mask to help protect against COVID-19 walks along a narrow street in Wuhan in central China's Hubei Province, Sunday, Jan. 23, 2022. Sunday will mark two years since the city of Wuhan was placed under a 76-day lockdown as China tried to contain the first major outbreak of the coronavirus pandemic. (AP Photo)