Protesters said that those arrested in the confrontation had numbers written on their arms and were housed in what appeared to be dog kennels, without bedding or furniture. Others said advancing officers sprayed mace and pelted them with rubber bullets.
It goes back to concentration camp days, said Mekasi Camp-Horinek, a protest coordinator who said authorities wrote a number on his arm when he was housed in one of the mesh enclosures with his mother, Casey.
At least 141 people were arrested Thursday after hundreds of police officers in riot gear, flanked by military vehicles releasing high-pitched sound cannon blasts, moved slowly forward, firing clouds of pepper spray at activists who refused to move.
Authorities claimed some protesters turned violent during the confrontation, setting fires, tossing Molotov cocktails and, in one instance, pulling out a gun and firing on officers.
Some of the activists claimed Friday that police had opened fire with rubber bullets on protesters and horses. One horse was euthanized after being shot in the leg, said Robby Romero, a Native American activist.
They were shooting their rubber bullets at our horses, he said. We had to put one horse down, he said.
Camp-Horinek said authorities entered the teepees that activists had erected in the path of the pipeline, a four-state, 1,200-mile conduit to carry oil from western North Dakota to Illinois.
It looked like a scene from the 1800s, with the cavalry coming up to the doors of the teepees, and flipping open the canvas doors with automatic weapons, he said.