A bus carrying about 50 passengers plunged into a river 25 miles (40 kilometers) west of Kathmandu on Friday, police said.
At least 14 people -- 11 men and three women -- died and 26 were injured, a police official said, reported CNN.
The initial investigation found the bus driver allowed his assistant to drive because he was sleepy, police said.
The bus was traveling from the border town of Birgunj, in the south, to Kathmandu when it was wrecked in Bhumistan, in Dhading district, police said.
Old buses, inexperienced drivers and poor roads in the mountains of Nepal combine to make bus crashes a common occurrence there.