The plane, a Bombardier Dash 8 Q400, with 67 passengers and four crew members caught fire after it careened off the runway during landing and crashed onto a football ground near the airport, TIA spokesperson Prem Nath Thakur said.
"Over 50 people are feared dead. We are carrying out rescue work. We are collecting details," Raj Kumar Chhetri, TIA General Manager, was quoted as saying by My Republica.
It said more than 20 injured were taken to Kathmandu Medical College for treatment of which seven were brought dead at the hospital. The remaining are undergoing treatment for serious burn injuries.
Plumes of black smoke could be seen rising from the football ground where the plane crashed.
"The plane shoot off the runway while it was about to crash into the hanger and immediately caught fire," an airport official was quoted as saying by the Himalayan Times.
The officials, however, have said a technical glitch could be the cause of the accident.
"The aircraft was permitted to land from the Southern side of the runway over Koteshwor but it landed from the Northern side," Director General of Civil Aviation Authority of Nepal (Caan) Sanjiv Gautam was quoted as saying by the Kathmandu Post.
He said the plane was out of control when it attempted to land on the runway.
"We are yet to ascertain the reason behind the unusual landing," he said suspecting the aircraft might have sustained some technical glitches.
Authorities say the fire has now been extinguished and rescue work is on.
All the flights to and from TIA have been halted after the crash.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)