Video: Highway drama as truck drags car for 6km

The bizarre scene of a truck dragging a car stuck to its side for 6km along a busy California highway has been caught on camera.

On Wednesday afternoon the truck, hauling tonnes of carrots, changed lanes and struck the side of the red Nissan Maxima, California Highway Patrol says.

The Maxima became lodged under the truck and the car, with its 34-year-old driver, was dragged along, KTLA reports.

Brian Steimke was in a car behind, and caught the drama on his phone.

Video shows the smoking car skidding along on the truck's side. Mr Steimke drives alongside the perilously trapped vehicle and the driver waves at him crying out: "Stop! He's not stopping!"

The car's windscreen is smashed, the bonnet is crumpled and the airbag has burst out of the dashboard. The tyres are burst and bouncing along the concrete.

The truck's driver Pete Maestas finally realises and stops. Mr Steimke pulls over and confronts Mr Maestas.

"I didn't know it," the driver responds.

"What do you mean you didn't know, dude? He's on your truck," Steimke is heard saying.

After police arrived at the scene Mr Maestas was allowed to drive away. The driver of the car was uninjured.

On Facebook Mr Steimke says the car was dragged "at least 4 miles".