Story highlights

The bus was carrying 41 people

17 of them were rescued

Three others are unaccounted for

New Delhi CNN  — 

A passenger bus plunged into the Trishuli River in central Nepal, killing 21 people.

The bus was carrying 41 people, 17 of whom were rescued and three others were unaccounted for, said chief officer Binod Kumar Singh of Chitwan District.

The bus had been traveling from Rautahat to the tourist town of Pokhara when it fell off the road and tumbled down 100 meters (328 feet) around 5 a.m. local time.

“Investigations are underway to find out the cause of the accident,” Singh said.

Last week, a passenger bus skidded off the road in central Nepal, killing at least 33 people and injuring 38 others. In that accident, the bus plunged more than 300 meters (about 985 feet) off a hill.

Developing story - more to come