At least four students were killed and more than 40 injured in a bomb explosion on Wednesday near a school bus in Balochistan province, according to Xinhua news agency, citing police and government officials.

The explosion occurred when the school bus carrying children and staff passed a vehicle loaded with explosives parked on the side of the road in the zero point area of Khuzdar district, said Khuzdar Deputy Commissioner Yasser Iqbal Dashti. Witnesses in the area reported that the bus was completely destroyed by the powerful explosion.

No group has claimed responsibility for the attack yet.