Authorities in North Dakota used tear gas, water hoses, percussion grenades, and rubber bullets on protesters against the Dakota Access Pipeline late Sunday night, according to reports. “They were attacked with water cannons,” said LaDonna Brave Bull Allard, a Standing Rock Sioux tribe member. “It is 23 degrees out there with mace, rubber bullets, pepper spray, etc. They are being trapped and attacked. Pray for my people.” Meanwhile, officials with the Morton County Sheriff’s Department called the incident an “ongoing riot” and protesters “very aggressive.” A spokesman said officers were spraying water because protesters lit fires on and around a strategic bridge. The tribe fears the oil pipeline will threaten their source of water and that construction has already disturbed sacred burial grounds.