The aircraft belonging to the private Agni Airlines, was carrying 11 passengers and three crew members. It crashed near Shikharpur village in Makawarnur district, about 80 kilometers south of Kathmandu.
The German-built Dornier plane was en route to Lukla, a popular trekking spot in the Everest region of eastern Nepal, from Kathmandu when the incident occurred, the Himalayan Times reported.
Officials at the police headquarters in Kathmandu said six foreigners were on board the ill-fated plane.
No further details were available.
Heavy torrential rains since Monday and fog have been hampering the rescue process.
The accident site is accessible only by foot, but the route from the nearest town is blocked by a river that is in spate.
The last major air crash in Nepal was in 2008 when a Twin Otter plane carrying 18 people crashed at Lukla killing everyone on board.