Opponents of the Dakota Access Pipeline found themselves face to face with North Dakota law enforcement again on Wednesday as they tried holding a ceremony on what authorities said was private land.

The latest confrontation began as about 200 protesters swam and paddled across the Cantapeta Creek in boats while others tried crossing a makeshift bridge built overnight across the waterway to reach property owned by the pipeline builder, according to the Morton County Sheriff’s Department.

The pipeline opponents, many of them from the local Standing Rock Sioux tribe, said they planned to hold a peaceful water ceremony but officers doused them with pepper spray or mace. Witnesses said some people were shot at close range with rubber bullets.

“It’s not safe here anymore. There’s too much going on right now,” said Kandi Mossett of the Indigenous Environmental Network.”It’s a very scary and tense situation being in the camp, and it goes hour by hour.”

The Morton County Sheriff’s Department confirmed using “less-than-lethal ammunition to control the situation,” as well as pepper spray and tear gas. The bridge was dismantled, they said.

One man was arrested and charged with conspiracy to commit obstruction of government function for allegedly purchasing canoes and kayaks for protesters, according to the sheriff’s office.

In a shift in policy, the Army Corps of Engineers on Tuesday ordered sheriff’s officers to arrest anyone who entered a section of Corps land north of the main camp, according the sheriff’s office.

Heavily armed police at #StandingRock in a boat that reads "Game Warden" #NoDAPL pic.twitter.com/3zWzQRN76R — Alexander Rubinstein (@AlexR_DC) November 2, 2016

On Thursday, authorities arrested 141 people while removing protesters, who prefer to be called water protectors, from a highway barricade and a camp blocking the path of the 1,172-mile pipeline. Authorities have tolerated a separate, larger encampment on federal land, but Morton County Sheriff Kyle Kirchmeier bristled at protesters’ expanded presence on private land.

“We cannot have protesters blocking county roads, blocking state highways or trespassing on private property,” Kirchmeier said last week.

It was perhaps the most chaotic day in months of demonstrations, as protesters allegedly set fires and threw objects at law enforcement who fired back with rubber bullets and pepper spray.

One woman faces multiple charges, including attempted murder, for allegedly firing a gun near sheriff’s deputies. Three others remained jailed on lesser charges as of Tuesday night because “they have to have written permission to stay at a local address and have not acquired that yet,” Morton County Sheriff’s Department spokeswoman Donnell Hushka said in an email.

The Standing Rock Sioux have called for a federal investigation into alleged civil rights violations by local and state law enforcement.

The tribe opposes the project because they fear a pipeline leak under the Missouri River would contaminate their drinking water. They also say the project’s construction disturbs sacred land covered by an 1851 treaty with the federal government.

Opposition has also sprouted in Iowa, where farmers were forced to cede land through eminent domain to make way for the pipeline.

Energy Transfer Partners, the company building the pipeline from North Dakota’s Bakken oil fields to existing infrastructure in Illinois, has said it is a safer method of moving crude than by truck or train.

North Dakota state officials rebuked the company Wednesday for possibly mishandling American Indian artifacts found last month during construction, according to The Associated Press.

President Barack Obama offered a glimmer of hope to the tribe Tuesday night when he said in an interview that the Army Corps is examining if the pipeline can be re-routed.

“We applaud President Obama’s commitment to protect our sacred lands, our water, and the water of 17 million others,” Standing Rock Sioux Chairman Dave Archambault said in a statement Wednesday. “While the Army Corps of Engineers is examining this issue we call on the administration and the Corps to issue an immediate ‘stop work order’ on the Dakota Access Pipeline. And given the flawed process that has put our drinking water in jeopardy, we also urge the Administration to call for a full environmental impact study.”