Amassive blast in northern Pakistan targeted a bus carrying Chinese engineers and Pakistani soldiers. As many as nine Chinese nationals and three Pakistani nationals died in the powerful explosion on Wednesday morning, the Chinese embassy confirmed.

An IED blast targeted the bus, which has led to at least 10 deaths so far, including that of 6 Chinese engineers and 2 Pakistani soldiers. Several others have suffered injuries and are in critical condition, reported Reuters from Pakistan.

The bus was carrying Chinese engineers who are working on the Dasu Dam. There were at least 30 engineers and workers travelling on the bus. There is a fear of the toll rising further as several injured are critical.

Meanwhile, China has asked Pakistan to thoroughly investigate the bus blast that killed at least 10 people, including Chinese nationals.

“There is a huge explosion in the bus carrying the Chinese engineers … in Upper Kohistan. Eight people lost their lives,” a senior administrative officer of the Hazara region told Reuters. Two paramilitary security men with the engineers also died, he added.

It was not immediately clear if the blast was the result of a roadside device or something planted inside the bus.

“The bus plunged into a deep ravine after the blast and caused heavy losses. One Chinese engineer and one soldier are missing. The rescue operation is launched and the entire government machinery has been mobilised to rescue the injured by air ambulance,” the senior government official told Reuters on condition of anonymity.

Chinese engineers and Pakistani construction workers have been working on the Dasu hydroelectric project for several years in the region where the blast took place.