A Pakistan International Airlines Airbus jet with 99 people on board has crashed into residential buildings in the Pakistani city of Karachi while approaching the airport.
At least two passengers survived but many others are feared dead.
At least 41 people are confirmed to have been killed, Pakistan International Airlines' (PIA) chief executive Arshad Malik said.
Smoke billowed from the scene where flight PK 8303 came down at about 2:45pm local time on Friday.
Twisted sections of fuselage lay in the rubble of multi-storey buildings as ambulances rushed through chaotic crowds.
At least two passengers survived - including Bank of Punjab President Zafar Masood, the Sindh provincial government said.
The bank said he had suffered some fractures but was "conscious and responding well".
Jinnah Hospital executive director Seemin Jamali said 17 dead bodies and six wounded people had been brought in.
There were no estimates of casualties on the ground.
"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, just as Pakistan was resuming domestic flights in the wake of the coronavirus pandemic, according to the aircraft tracking website FlightRadar24.
The crash happened on the eve of the Muslim festival of Eid, when Pakistanis traditionally travel to visit relatives.
The plane was on its second attempt to land after cancelling a previous one in a routine manoeuvre known as a go-around, one person familiar with the investigation said.
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!".
There was no further communication from the plane, according to the tape, which could not immediately be authenticated.
"The last we heard from the pilot was that he has some technical problem," the state carrier's spokesman Abdullah H Khan said.
"He was told from the final approach that both the runways were ready where he can land, but the pilot decided that he wanted to do (a) go-round ... It is a very tragic incident."
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, but it was too early to determine the cause.
Army and rescue services rushed to the area, which appeared to be densely populated. Footage showed cars on fire.
Prime Minister Imran Khan tweeted that he was "shocked & saddened by the PIA crash".
"Am in touch with PIA CEO Arshad Malik, who has left for Karachi & with the rescue & relief teams on ground as this is the priority right now," Khan said.
"Immediate inquiry will be instituted. Prayers & condolences go to families of the deceased."