Twenty-three people were killed in southwestern Nepal when a bus carrying students and teachers back from a field trip veered off a road and plunged into a gorge on Friday, PTI reported. The bus was carrying 37 people – 34 students, two teachers and a driver.

Police officer Prem Bahadur Shahi told Al Jazeera that the bus was returning to Ghorahi town from an educational trip to Dang district when the accident took place near Tulsipur town on Friday. “It plunged about 700 metres below the road,” Shahi said, adding that the bodies of 16 people have been recovered so far.

Police said 14 people who were injured in the incident are undergoing treatment at a local hospital, reported The Kathmandu Post.

“Our preliminary investigation shows the cause of the incident was speed,” police officer Bel Bahadur Pandey told AFP. The students and teachers were from the Krishna Sen Ichhuk Polytechnic Institute and were visiting a farm in a nearby district for their botany field trip.

Last week, 20 people were killed when a mini-truck skidded off the road in Nuwakot district in central Nepal.