BISMARCK, N.D. (AP) – Law enforcement officers have been called to southern North Dakota to keep the peace between American Indian protesters and developers of the $3.8 billion Dakota Access Pipeline from North Dakota to Illinois.

Native Americans have been staging a nonviolent protest for months at a “spirit camp” established by the Standing Rock Sioux at the confluence of the Cannonball and Missouri rivers.

Highway Patrol Lt. Tom Iverson says construction crews with armed security were in the area on Wednesday but were initially blocked by protesters. He says troopers are helping the Morton County Sheriff’s office.

Iverson says no arrests were reported.

Tribal member LaDonna Brave Bull Allard says about 45 construction vehicles were backed up on roads Wednesday afternoon. She says protesters have been peaceful.