MANDAN, N.D. — Law enforcement authorities in North Dakota say 21 people protesting at two construction sites of the Dakota Access pipeline have been arrested.

The Morton County Sheriff’s Office says the individuals were arrested Wednesday on charges including resisting arrest, criminal trespass on private property and possession of stolen property.

The sheriff’s office says officers responding to the sites near the community of St. Anthony found several people and horses on private property.

The agency says an officer had to raise his weapon “containing less-lethal ammunition” after a protester on horseback charged at him. The officer wasn’t injured.

Morton County Sheriff Kyle Kirchmeier says the charging horse combined with the rest of the situation presented an “imminent threat” to the officer.

The statement says 95 people have been arrested in recent weeks since protests began months ago over the four-state, $3.8 billion pipeline.