A crash between an oil tanker and a passenger bus killed at least 20 people in northeastern Pakistan on early Tuesday morning, officials said.

The collision – the second in less than a week – took place near the northeastern city of Multan on a motorway when the bus heading from Lahore to Karachi hit the oil tanker, carrying thousands of liters of petrol, from the rear side, Tahir Wattoo, deputy commissioner of Multan, said in a statement.

The collision resulted in a huge fire that engulfed both vehicles, killing 20 people on the spot, while another six sustained critical injuries, he added.

Images shared by the district administration showed the ill-fated bus and the oil tanker lying completely charred in the middle of the road.

Quoting motorway police, local broadcaster Dawn News reported that the bus driver fell asleep, which caused the fatal accident.

On Saturday, at least 13 people were killed and five injured in a collision between a passenger van and a truck on a highway in Rahim Yar Khan, a district in Punjab province, some 590 kilometers (365 miles) from the provincial capital Lahore.

Fatal road accidents are common in this South Asian country, mainly due to lax safety and infrastructure standards.