More than a dozen people, including Chinese nationals and Pakistani soldiers,
were killed in a blast targeting a bus in a remote region of northern Pakistan on Wednesday.
That's according to multiple sources who said the toll could rise.
It was not immediately clear whether the blast was the result of a roadside device or something planted inside the bus.
Inspector general Moazzam Jah Ansari said the bus plunged into a ravine.
Bomb disposal experts were at the scene, and police were investigating what he said looked like sabotage.
Beijing condemned the blast and asked Pakistan to punish the perpetrators
and protect the safety of Chinese personnel, institutions and projects.
A senior administrative officer of the Hazara region said
the bus was carrying more than 30 Chinese engineers to the site of the Dasu dam in Upper Kohistan.
The Dasu hydroelectric project is part of the China-Pakistan Economic Corridor (CPEC), which is a $65 billion investment plan.
It falls under Beijing's Belt and Road initiative, aimed at connecting western China to the Gwadar sea port in southern Pakistan.