MANSEHRA: A Chinese delegation on Thursday visited the Barseen area of Upper Kohistan where a high-level investigation is underway to determine whether the explosion inside a coach -- which was carrying the Chinese workers to the under-construction Dasu dam -- was a subversive act or a technical fault that caused the engine to explode. At least 13 people, including nine Chinese nationals, were killed and 14 others injured in the tragedy. A joint investigation team comprising experts from Pakistan Army, police, CTD, bomb disposal unit of KP found traces of explosives around the area where the coach had fallen into the gorge.