Law enforcement officials arrested dozens of activists protesting the construction of the Dakota Access pipeline and shot at a drone over the weekend.
A helicopter monitoring the protests, which blocked a North Dakota state highway twice on Sunday, was approached by a drone.
According to CNN, the activists were using the drone to document police encounters.
The Morton County Sheriff's Office released a statement saying the drone approached in a "threatening manner" and the pilot and passengers were "in fear of their lives."
Authorities fired at the drone and damaged it, forcing the operator to land it.
Morton County Sheriff Kyle Kirchmeier told CBS News that the drones flying near the protests aren't being operated according to federal regulations. He added that the two people operating drones have already been charged.
The Morton County Sheriff's Office told CNN that about 300 protestors trespassed on private property three miles west of State Highway 1806 Saturday.
At least 127 people were arrested on charges ranging from reckless endangerment to criminal trespass.
More than 260 people have bee arrested since demonstrations began in August.
Authorities told CBS News that some of the protestors have gone so far as to place tents on private property along the pipeline construction route.
Energy Transfer Partners is buidling the $3.8 billion pipeline, which spans four states including North Dakota, South Dakota, Iowa and Illinois.
Those opposed to the pipeline fear the potential effects it could have on drinking water on the Standing Rock Sioux's reservation. In addition, the tribe has noted that the pipeline would destroy cultural artifacts.
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