BISMARCK, N.D. (AP) — Law enforcement officers from several states are heading to North Dakota to help authorities deal with the protest over the Dakota Access pipeline.

Morton County Sheriff Kyle Kirchmeier said at a news conference Monday that authorities put out a call for extra officers earlier this month.

Kirchmeier says departments from Wisconsin, South Dakota, Minnesota, Wyoming, Indiana and Nebraska are sending officers.

The protesters, many of whom are Native Americans, have been demonstrating against the four-state pipeline for months. A group over the weekend set up tents and teepees on private property owned by the pipeline development. A sheriff’s office spokeswoman said earlier Monday that Morton County doesn’t currently have the manpower to remove them.

More than 260 people have been arrested since demonstrations began in August. Nearly half of those were arrested over the weekend during a large protest at a pipeline construction site.