A woman who only wanted to be identified as Roxy watched the helicopters from Backwater Bridge just north of the main camp.

“We felt helpless. We’re trying to protect our water and then somebody did this,” she said.

While it wasn’t known who started the fire, Frank Archambault said security was told by tribal elders to “get a grip” on destructive activity – including the burning of vehicles on the bridge – in order to maintain a peaceful and prayerful protest.

“We are not condoning anything like that,” he said. “We are trying to get a hold of the radicals and get them dismissed.”

Some pipeline opponents said they believe the state is purposely keeping Backwater Bridge blocked as a stalling tactic to keep protesters away from the Dakota Access construction site on the other side. But Preskey said the bridge is not being cleared because the burned vehicles are still smoldering and the state Department of Transportation has deemed the bridge unsafe for anyone to cross. It will remain closed until bridge engineers evaluate damage to the structure, the DOT said Friday.