An explosion in a Chinese expressway tunnel on Friday was caused by a collision between two oil tankers, reported the government-run Xinhua news organisation.

The tunnel, in the northwest of China on the Lanzhou City to Linxia Hua autonomous region link, was ‘shrouded in vapour’, according to witnesses, as a ten-strong fleet of fire engines fought to contain the blaze.

Rescue work in the tunnel was difficult due to the incredibly high temperature caused by the inferno, which was since doused. Four bodies have been removed from the tunnel and three vehicles were ‘mangled’, including the colliding tankers.

Damage to the tunnel facilities was reported but has not been specified. The expressway was still closed to traffic as T&TI went to press. Rescue workers believed that more people were possibly trapped in the tunnel.