Drivers have been caught in a six kilometre traffic jam on the M4 this afternoon.

A truck and three cars collided between James Ruse Drive and Silverwater Road at Auburn.

All city bound lanes had to be closed while the crash scene was cleared, and fuel spilled onto the road was cleaned up.

Two children and an adult were treated by paramedics, but Seven News understands that their injuries weren't serious.

Gallery - Traffic is banked back six kilometres after an accident involving a truck and three cars at Auburn. Photo: 7News