This horrific footage captures an apparent road rage row sparking a serious crash on a motorway.
A motorcyclist and a driver appeared to be engaged in a confrontation as they sped down a freeway in Los Angeles.
In the dashcam video posted online, the motorcyclist kicks out at the car.
The driver then appears to lurch to the left in retaliation, but then crashes into the central reservation.
The person recording the video gasps in shock as the car then careers back across three lanes of the freeway and hits another oncoming truck.
The truck driver had no chance of getting out the way and ends up flipping over.
California's Highway Patrol in investigating the crash and officers want to speak to the motorcyclist who didn't stop at the scene.
They asked for witnesses to come forward.