Law enforcement officers were "pulled back from the area because it was determined that, at that point, it was unsafe for them to go into the situation," Kirchmeier said.

“At this point ... I don’t believe that we need to go in there and have physical altercations with the protesters,” he said.

On Saturday, the Morton County Sheriff's Department said three private security guards working for the Dakota Access Pipeline were reportedly injured after about 300 protesters entered the work site. One guard was transported to a Bismarck hospital, but refused treatment.

No arrests have been made as a result of the incident that occurred Saturday or Tuesday.

“We are actively investigating these incidents, either by video or social media to identify people that have taken place in this,” Kirchmeier said. “We will pursue charges as needed.”

Standing Rock Sioux Tribal Chairman Dave Archambault II compared illegal actions taken by protesters, like those that bound themselves to equipment, to Rosa Parks refusing to give up her bus seat during the Civil Rights movement: "It was illegal but it was the right thing to do."