A toxic gas leak killed four more people in Pakistan's southern port city of Karachi, police said Tuesday, bringing the death toll so far to nine in the incident that has sickened hundreds and mystified authorities.

The new deaths have set off a panic in Karachi and raised concerns that the city's government, which has failed to identify the source of the leak and the type of gas involved, is at a loss in dealing with the situation, though officials insist there is no suspicion of sabotage.

The apparently odorless gas, which causes severe breathing problems, has sickened hundreds since the leak first struck in Karachi's coastal neighborhood of Kamari on Sunday night, when people suddenly started rushing to local hospitals.

People carry the body of a victim of a toxic gas leak, during his funeral prayer, in Karachi, Pakistan, Monday, Feb. 17, 2020. The toxic gas leak killed several people and sickened dozens of others in a coastal residential area in Pakistan's port city of Karachi, police said Monday. The source of the leak, which occurred on Sunday night, and the type of gas that had leaked were not immediately known. There was no suspicion of sabotage. (AP PhotoFareed Khan)

People carry the body of a victim of a toxic gas leak, during his funeral prayer, in Karachi, Pakistan, Monday, Feb. 17, 2020. The toxic gas leak killed several people and sickened dozens of others in a coastal residential area in Pakistan's port city of Karachi, police said Monday. The source of the leak, which occurred on Sunday night, and the type of gas that had leaked were not immediately known. There was no suspicion of sabotage. (AP PhotoFareed Khan)

Authorities said they were planning to evacuate residents from Kamari, which is close to the main port where incoming ships anchor, to safer places by Tuesday evening.

The initial death toll on Monday morning stood at five but Adil Malik, a local police chief, said about 150 people more were rushed to hospitals by the evening, with the same symptoms, and the death toll subsequently rose to nine.

All the stricken people — hospitals said they had treated more than 650 — were residents of Kamari. No cases were reported in the port itself.

Private guards wear masks while standing outside a hospital, where victims of toxic gas leak are treated in Kamari neighborhood of Karachi, Pakistan, Monday, Feb. 17, 2020. A toxic gas leak killed five people and sickened dozens of others in a coastal residential area in Pakistan's port city of Karachi, police said Monday. The source of the leak, which occurred on Sunday night, and the type of gas that had leaked were not immediately known. There was no suspicion of sabotage. (AP PhotoFareed Khan)

Private guards wear masks while standing outside a hospital, where victims of toxic gas leak are treated in Kamari neighborhood of Karachi, Pakistan, Monday, Feb. 17, 2020. A toxic gas leak killed five people and sickened dozens of others in a coastal residential area in Pakistan's port city of Karachi, police said Monday. The source of the leak, which occurred on Sunday night, and the type of gas that had leaked were not immediately known. There was no suspicion of sabotage. (AP PhotoFareed Khan)

“There are thousands of shipping containers in the port area and authorities are checking them to determine if the toxic gas emitted from there," Malik said.

A patient in a Karchi hospital, Babar Bahadur, said Monday that he first felt an ache in his eyes and pain in chest.

“My heart started beating suddenly very, very fast," he told The Associated Press and recounted how he immediately rushed to the hospital where he was treated and felt better “after quite some time."

He said his son experienced some of the same symptoms and was also briefly treated at the hospital.

Port officials insisted no gas leaks occurred at any of their facilities.

Karachi is the capital of southern Sindh province, Pakistan's largest city and the country's chief commercial hub. It has oil refineries nearby and a key installation of Pakistan's navy is also located there.