The American Civil Liberties Union is blasting police for using what it terms “life-threatening crowd-control weapons” against demonstrators seeking to halt construction of the #Dakota Access Pipeline.

In a violent confrontation between hundreds of protesters and officers in sub-freezing weather Sunday night, police used water cannons to push back and soak the demonstrators, while also firing rubber bullets and lobbing tear gas canisters into the crowd. Protest leaders say nearly 200 people were hurt, some seriously.

The protesters -- who call themselves “water protectors” -- are trying to stop pipeline company Energy Transfer Partners from building the final segment of a 1,200-mile pipeline that would take it under a reservoir that provides water for the Standing Rock Sioux reservation. The protesters, who have been camped out for months, say a leak in the pipeline would contaminate the tribe's drinking water. They also say building the pipeline threatens sacred land.

Sheriff's officials defend use of water cannons

Morton County sheriff’s officials are defending their tactics, saying during Sunday night’s melee they were dealing with an “ongoing riot” and that protesters were “very aggressive.” But various videos posted on the internet show police dousing protesters with the water cannons as the protesters milled about or stood at a distance, some raising their hands and posing no apparent threat to law enforcement officers.

ACLU says water cannons can kill

Writing in the #ACLU”s blog, the director of the union’s Human Rights Program, Jamil Dakwar, noted the dangers to civilians when police use water cannons. Referencing a joint report prepared by the International Network of Civil Liberties Organizations and Physicians for Human Rights, Dakwar wrote that “water cannons are characterized as particularly dangerous and life-threatening weapons.”

“The use of water cannons can induce facial, skull, and rib fractures; brain trauma; bruises; prolonged nausea; and even blindness,” he wrote “Water cannons have been attributed to deaths in Indonesia, Zimbabwe, Turkey, South Korea, and Ukraine.”

ACLU seeks Justice Department investigation

The ACLU says besides local Morton County sheriff’s deputies on the scene, scores of police from various agencies have been called to Standing Rock. The union is calling on the U.S. Justice Department to investigate possible constitutional violations. It also wants the federal government to stop providing police agencies with military equipment.

Veterans group to join protesters

Meanwhile, hundreds of veterans -- including Wesley Clark Jr. -- a former Army officer and son of the more well known general with the same name -- are heading to North Dakota next month as part of what they’re terming a “peaceful, unarmed militia.” Organizers of a group calling themselves “Veterans Stand for Standing Rock” are urging other veterans to come with them as they join in the protest for three days, beginning Dec. 4.

The veterans group has set up a gofundme page to raise money to pay for food, gas and expenses for the effort. Through late Wednesday more than $131,000 in donations had been contributed.

For its part, Dallas-based Energy Transfer Partners says it has gone through an extensive approval process to build and complete the pipeline, and that there are a number of safeguards in place to prevent ruptures or leaks. Company officials and backers of the project also argue pipelines are safer and a more efficient method than trucks or trains in transporting oil. #NoDAPL