A Pakistan International Airlines jet with 99 people on board has crashed into a crowded residential district of the city of Karachi while approaching the airport.
At least 56 people are confirmed to have died, hospital officials said.
Other officials gave different figures and authorities did not release an estimate of casualties on the ground.
Two passengers survived, including Bank of Punjab president Zafar Masood, a Sindh provincial government spokesman said.
The bank said he had suffered fractures but was “conscious and responding well”.
The other survivor, engineer Muhammad Zubair, told Geo News the pilot came down for one landing, briefly touched down, then took off again.
After around 10 more minutes of flying, the pilot announced to passengers he was going to go around for a second go, then crashed as he approached the runway, Zubair said from his bed in Civil Hospital Karachi.
“All I could see around was smoke and fire,” he said.
Smoke billowed from the scene where flight PK 8303 came down at about 2.45pm local time on Friday.
Twisted fuselage lay in the rubble of multi-storey buildings as ambulances rushed through chaotic crowds.
The crash happened on the eve of the Muslim festival of Eid, when Pakistanis travel to visit relatives.
“The aeroplane first hit a mobile tower and crashed over houses,” witness Shakeel Ahmed said near the site, a few kilometres short of the airport.
The Airbus A320 was flying from the eastern city of Lahore to Karachi in the south with 91 passengers and eight crew, civil aviation authorities said.
Pakistan has only just resumed domestic flights in the wake of the coronavirus pandemic.
A total of 56 bodies were brought to JPMC hospital and the Civil Hospital Karachi, officials from both institutions said.
Seconds before the crash, the pilot told air traffic controllers he had lost power from both engines, according to a recording posted on liveatc.net, a widely respected aviation monitoring website.
“We are returning back, sir, we have lost engines,” a man was heard saying in a recording released by the website.
The controller freed up both the airport’s runways but moments later the man called “Mayday! Mayday! Mayday!”.
“The last we heard from the pilot was that he has some technical problem … It is a very tragic incident,” the state carrier’s spokesman Abdullah H Khan said.
Another senior civil aviation official told Reuters it appeared the plane had been unable to lower its undercarriage for the first approach due to a technical fault.
Prime Minister Imran Khan tweeted that he was “shocked & saddened by the PIA crash”.
“Immediate inquiry will be instituted. Prayers & condolences go to families of the deceased,” he posted.
The Department of Foreign Affairs and Trade is working to determine if any Australians were on board the flight.