The Morton County sheriff’s office says about 300 protesters trespassed three miles onto private property Saturday morning. The sheriff’s office says officers used pepper spray when some protesters attempted to breach a line that law enforcement officers had formed between demonstrators and construction equipment.

Authorities say the confrontation between officers and protesters lasted five hours.

The sheriff’s office says one protester attempted to grab an officer’s pepper spray canister, spraying the officer in the face and blinding him for five minutes.

Sheriff Kyle Kirchmeier says Saturday’s incident shows that “this protest is not peaceful or lawful.”

Charges against the individuals include assault on a peace officer, engaging in a riot and criminal trespass.