The plane was carrying two crew members and 17 technicians to Pokhara city to repair another aircraft, officials said.
"Only the captain was rescued alive and is receiving treatment at a hospital," said Tej Bahadur Poudyal, the spokesman for Kathmandu's Tribhuvan International Airport.
Television visuals showed fire fighters trying to put out the blaze and thick black smoke rising into the sky. They also showed the plane flying a little above the runway and then tilting before it crashed, Reuters reported.
Other visuals showed rescue workers rummaging through the charred remains of the plane, strewn in lush green fields.
Bodies were carried to ambulances on stretchers as local residents looked on, the television showed.
The plane was a Bombardier (BBDb.TO), opens new tab, officials said, and media reported it belonged to local Saurya Airlines. The airport had been temporarily closed, the officials added.
Saurya operates domestic flights in Nepal with two Bombardier CRJ-200 regional jets, both around 20 years old, according to Flight Radar 24.
Nepal has been criticized for a poor air safety record, and nearly 350 people have died in plane or helicopter crashes in the Himalayan country since 2000.
The deadliest incident occurred in 1992, when a Pakistan International Airlines Airbus crashed into a hillside while approaching Kathmandu, killing 167 people.
Most recently, at least 72 people were killed in a Yeti airlines crash in January 2023 that was later attributed to the pilots mistakenly cutting off power.