Hundreds of Native American protestors and their supporters, who fear the Dakota Access Pipeline will polluted their water, forced construction workers and security forces to retreat and work to stop. / AFP / Robyn BECK (Photo credit should read ROBYN BECK/AFP/Getty Images)

A protestor is treated after being pepper sprayed by private security contractors on land being graded for the Dakota Access Pipeline (DAPL) oil pipeline, near Cannon Ball, North Dakota, September 3, 2016.

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BISMARCK, N.D. – A protest of a $3.8 billion oil pipeline has turned violent after protesters say private security has been using pepper spray and dogs to contain them.

Standing Rock Sioux Tribe spokesman Steve Sitting Bear told CBS that the protesters reported that six people had been bitten by security dogs, including a child.

Also, at least 30 people were pepper-sprayed.

Morton County Sheriff’s Office spokeswoman Donnell Preskey says she had no reports of protesters being injured, despite video surfacing on social media of dog bites and protesters being sprayed.

Warning: Explicit language is used in the video and is not appropriate for all audiences.

On the other hand, Preskey said that two dogs and four private security guards were injured during a confrontation between construction crews and protesters.

Vicki Granado, a spokeswoman for Energy Transfer Partners told CBS that the protesters broke through a fence and “attacked” the workers.

Morton County Sheriff Kyle Kirchmeier said in a statement that “individuals crossed onto private property and accosted private security officers with wooden posts and flag poles.”

The whole situation stems from an oil pipeline that is supposed to be built in the area near the tribe’s land. The proposed Dakota Access Pipeline would transport crude oil from North Dakota through South Dakota and Iowa and into Illinois. The underground pipeline would transport 470,000 barrels of crude oil a day, which would be sent to markets and refineries in the Midwest, East Coast and Gulf Coast regions, according to Energy Transfer Crude Oil Co.

Tribal leaders say they fear the pipeline will destroy sacred sites and contaminate drinking water.

“We have laws that require federal agencies to consider environmental risks and protection of Indian historic and sacred sites,” Dave Archambault II, the elected chairman of the Standing Rock Sioux Tribe, said in a statement. “But the Army Corps has ignored all those laws and fast-tracked this massive project just to meet the pipeline’s aggressive construction schedule.”