KATHMANDU, Nepal — Authorities say a truck carrying construction workers fell off a mountain road in Nepal, killing at least 18 people and injuring 14 others.

The Mustang district administration office said the truck dropped about 50 meters (160 feet). Rescue helicopters took those injured in Friday's crash to hospitals for treatment.

The workers were heading to a road construction site.

Police were investing the cause of the accident, but the conditions of roads and vehicles in Nepal are often poor.

Narrow, gravel roads are typical in the mountainous area where the crash occurred, about 200 kilometers (125 miles) west of the capital, Kathmandu.