Dakota Access Pipeline protesters entered a work yard for pipeline equipment in Mandan early Saturday morning, prompting an evacuation of workers there.
Police are also investigating reports of shots fired at the site, according to Rob Keller, a spokesman for the Morton County Sheriff's Department.
Around 9 a.m., the sheriff's department received a phone call of 130 to 150 cars leaving the protests camps in southern Morton County and heading north on Highway 6 to Mandan, Keller said.
About an hour later, protesters then headed to a work yard, located on County Road 82 near the Mandan Landfill, Keller said. The protesters linked arms and blocked the entrance.
A video posted on social media showed a man driving a truck at protesters in the work yard. The man driving the truck in the video also had a gun pointed at protesters.
There was a report of a protester being injured, Keller said, however it's not clear how it happened. Keller said the protester refused medical treatment.
No arrests were made Saturday.