Four people have been killed after a truck struck two cars on a German highway, pushing the smaller vehicles under another trailer.

Mannheim police said the incident happened on the A5 Autobahn near the town of Walldorf in south-west Germany.

A woman was extracted from the wreckage and flown by helicopter to a hospital with serious injuries. The two truck drivers were unharmed.

A seven-car pileup in the opposite lane injured three people, in what police described as a "rubbernecking accident".

- PA