Update - 11.37am: Dozens of people have been killed after a passenger plane carrying 71 people from Bangladesh crashed and burst into flames as it landed in Kathmandu, Nepal's capital.
The death toll among those on board the US-Bangla Airlines flight remained unclear amid the chaos of the crash, with badly injured victims being rushed to nearby hospitals.
Nepal army spokesman Brigadier General Gokul Bhandari said 50 people had died and the fate of the others was unknown.
A police official said at least 38 people had died, 23 were injured and another 10 were unaccounted for.
An AP journalist who arrived at the scene soon after the crash saw the US-Bangla Airlines twin-propeller plane broken into several large pieces, with dozens of firefighters and rescue workers clustered around the wreckage in a grassy field near the runway.
Hundreds of people stood on a nearby hill, staring down at what remained of the Bombardier Dash 8.
The plane swerved repeatedly as it prepared to land in Kathmandu, said Amanda Summers, an American citizen working in Nepal. The crowded city sits in a valley in the Himalayan foothills.
"It was flying so low I thought it was going to run into the mountains," said Ms Summers, who watched the crash from the terrace of her home office, not far from the airport. "All of a sudden there was a blast and then another blast."
Fire crews put out the flames quickly, perhaps within a minute, she said, though for a time clouds of thick, dark smoke rose into the sky above the city.
The plane had circled the airport twice as it waited for clearance to land, Mohammed Selim, the airline's manager in Kathmandu, told Dhaka-based Somoy TV station by telephone.
Smoke seen from Kathmandu airport amid reports of a Bangla plane crash in Kathmandu pic.twitter.com/a2VL2rOrMG— Ankiit Koomar (@AnkiitKoomar) March 12, 2018
10.57am: At least 38 dead after passenger plane crash-lands at Nepal's Kathmandu airport
At least 38 people have been killed and 23 others were injured in a plane crash in Kathmandu, with another 10 still unaccounted for, Nepal police said.
The plane, a twin-propeller Bombardier Dash 8 flying from Bangladesh, swerved repeatedly before it crashed, landing near the runway.
9:39am - Passenger plane carrying 67 people crash-lands at Nepal's Kathmandu airport
A passenger plane from Bangladesh crashed as it landed at Kathmandu airport in Nepal, an airport official said.
The US-Bangla aircraft was said to be carrying 67 people.
— Amjad Alam Hunzai (@amjadalamk) March 12, 2018
It was not clear if there were fatalities, but clouds of thick, dark smoke could be seen rising above the hilltop airport, which was immediately shut down.
The official said the flight was arriving from Dhaka, the Bangladesh capital.
Video shows firefighters at the site of a plane crash at Kathmandu airport in Nepal as the rescue operation continues. There were 67 passengers onboard, with 17 rescued so far. https://t.co/AUQEPjGPqw pic.twitter.com/lbfX2bhn98— ABC News (@ABC) March 12, 2018
He said the plane appeared to have caught fire just before it landed and skidded to a stop in a field beside the runway.
An employee who answered the phone at the US-Bangla offices in Dhaka said no one was available to talk.