CANNON BALL, N.D. - Some 400 people protesting the Dakota Access pipeline have been clashing with law enforcement in North Dakota.

Demonstrators have been trying to cross a bridge on state Highway 1806 in Morton County.

Officers formed a line to stop the protesters from pushing past, and it appears the officers have been using water cannons.

The pipeline has been protested for months by the Standing Rock Sioux, whose reservation lies near the pipeline route.