A number of children have been injured in a crash between a truck and a bus north of Ashburton this afternoon.

The vehicles collided on State Highway 1 at Fairfield around 3.40pm.

Police said a number of children were receiving treatment for minor to moderate injuries, and hot tar from the truck had spilt across the road.

A portion of SH1 was closed while the road was cleared, and southbound detours were in place.