Searchers using planes, ships and satellites were combing Antarctic seas on Tuesday, hunting for a Chilean Air Force transport plane carrying 38 people that vanished en route to a base on the frozen continent.

Seven hours after contact was cut off, the Air Force declared the plane a loss, though there was no sign of what happened to it. The Air Force said two ships, more than a dozen planes and three satellites were being used in the search.

Officials said the plane had taken off in favorable conditions on Monday, though it was flying in an area notorious for rapidly changing conditions, with freezing temperatures and strong winds.

Relatives of passengers of a missing military plane are transported into the Cerrillos airbase in Santiago, Chile, Tuesday, Dec. 10, 2019. Chile's air force said it lost radio contact with a C-130 Hercules transport plane carrying 38 people on a flight to the country's base in Antarctica, and authorities are indicating they are not optimistic about the aircraft's fate. (AP PhotoLuis Hidalgo)

Relatives of passengers of a missing military plane are transported into the Cerrillos airbase in Santiago, Chile, Tuesday, Dec. 10, 2019. Chile's air force said it lost radio contact with a C-130 Hercules transport plane carrying 38 people on a flight to the country's base in Antarctica, and authorities are indicating they are not optimistic about the aircraft's fate. (AP PhotoLuis Hidalgo)

The C-130 Hercules carried 17 crew members and 21 passengers, including three civilians. They were en route to check on a floating fuel supply line and other equipment at the Chilean base.

President Sebastián Piñera said via Twitter that he was with his defense and interior ministers at the air force headquarters monitoring developments.

“My thoughts and prayers are with the families of the 38 crew members and passengers," Piñera said, adding that he had cancelled a planned trip to attend Tuesday's inauguration in Argentina of President Alberto Fernández.

Relatives of passengers of a missing military plane arrive at the Cerrillos airbase in Santiago, Chile, Tuesday, Dec. 10, 2019. Chile's air force said it lost radio contact with a C-130 Hercules transport plane carrying 38 people on a flight to the country's base in Antarctica, and authorities are indicating they are not optimistic about the aircraft's fate. (AP PhotoLuis Hidalgo)

Relatives of passengers of a missing military plane arrive at the Cerrillos airbase in Santiago, Chile, Tuesday, Dec. 10, 2019. Chile's air force said it lost radio contact with a C-130 Hercules transport plane carrying 38 people on a flight to the country's base in Antarctica, and authorities are indicating they are not optimistic about the aircraft's fate. (AP PhotoLuis Hidalgo)

The three civilian passengers included a 24-year-old who was embarking on a research project and two employees of a private company. One passenger was a woman.

The plane took off at Monday afternoon from the southern city of Punta Arenas, more than 3,000 kilometers (1,860 miles) from the capital of Santiago. Contact was lost at 6:13 p.m., the initial announcement said.

Drake's Passage, the sea between the southern tip of South America and Antarctica, is infamous for severe weather conditions, including ferocious storms. But the Air Force said late Monday that the weather was good when the plane began its flight, or the mission would not have been carried out.

Gen. Eduardo Mosqueira of the Fourth Air Brigade told local media that a search was underway and a ship was in the general area where the plane should have been when contact was lost.

“Antarctica is different. It's hard to fly because of changing conditions," Mosqueira said,

The aircraft would have been about halfway to the Antarctic base when it lost contact, Mosqueira said, adding that no emergency signals had been activated.