The mishap happened on Wednesday morning in Kohistan district of Khyber Pakhtunkhwa province. The bus was carrying a total of 41 people, Arif Khan, the Deputy Commissioner of the district, was quoted as saying by The Express Tribune.

Two security personnel are among the dead. Arif said all dead and injured were transported to a nearby hospital. Authorities are now investigating the cause of the accident.

Dozens of Chinese engineers are helping Pakistan build a dam in the mountainous district. Arif said the Pakistani and Chinese construction workers were on their way to the project site when the accident happened.

A delegation of senior provincial officials, including the chief secretary and the police chief, reached the spot following the incident, The Express Tribune reported.