Dakota pipeline: Will police crackdown dampen protests?

Pepper spray, fires

The message from law enforcement Thursday night was clear as Humvees and helicopters flooded the area to break up an encampment near the pipeline's path.

Police deployed beanbags, pepper spray gas and unleashed a high-pitched siren as they tried to disperse the crowd. Protesters lit debris on fire and threw Molotov cocktails, North Dakota Department of Emergency Services spokeswoman Cecily Fong said.

Demonstrators stand near burning tires as they face off with law enforcement Thursday.

Authorities accused most of the arrested demonstrators of trespassing on private property. Supporters of the Standing Rock Sioux Tribe had earlier set up tents and tepees on the land, which they said belongs to the tribe under a 19th-century treaty.

Dakota Access Pipeline: What's at stake?