A semi-trailer truck rear-ended two sedans on a road in northwest China's Qinghai Province on Sunday, leaving seven people dead and five injured, local police said.

The truck rear-ended a sedan and pushed it forward to hit another trailer running in the front. The sedan then strayed to a sign board on the side, leaving all of its five passengers dead.

Then the trailer decoupled from the truck and hit another sedan and injured four passengers inside. Two passengers in the truck died at the scene.

All the injured, including a critically injured child, have been rushed to hospital. Authorities are looking into the cause of the case.