A bus carrying college students and their instructors back from a botany field trip drove off a highway in a mountainous area on Friday, leaving 21 dead and 15 injured, police said. The bus plunged down a mountainous slope and rolled about 500 meters (1,640 feet), police said.

The Nepalese students and instructors from Krishna Sen Ichhuk Polytechnic Institute had been visiting a farm in a nearby district. Rescue operations were difficult at the crash site near Ramri village, about 400 kilometers (250 miles) west of the capital Kathmandu, because the crash happened in a remote area and the wreckage was scattered. The injured were taken to hospitals for treatment.