This story was updated on Feb. 23.

While many activists left the site of a months-long protest against the Dakota Access pipeline voluntarily as a deadline passed for them to clear the area on Wednesday, some protesters decided to defy the order to leave. Eventually, at least 40 were arrested at the site, according to law enforcement officials.

As the 2 p.m. deadline approached on Wednesday, a live video feed provided by the volunteer media group Unicorn Riot showed fires burning, apparently set by some protesters, as snow fell on a largely deserted site on the banks of the Missouri River near Cannon Ball, N.D. Law enforcement officers remained on the periphery as the deadline came and went.

The live video on Thursday showed that humvees and other armored vehicles had surrounded the area, as at least two bulldozers had entered the camp and begun clearing the grounds. By Thursday afternoon, the number of those arrested had reached at least 40.

Maxine Herr, a spokeswoman for the Morton County Sheriff’s Department, said that about 100 protesters boarded a bus and vans, provided by a local church, to travel to a center that the state had set up on Wednesday. She said anyone who arrived at the center would be given a voucher for food and one night at a hotel, as well as a one-way bus ticket home, wherever that may be.

Earlier on Wednesday, Chase Iron Eyes, a Standing Rock Sioux member, told Reuters that protesters would make their own decisions about whether to stay behind despite an order to leave. “Some will get arrested,” he said.

Gov. Doug Burgum issued an emergency order last week with the Wednesday deadline to the leave the site. State officials had said they are concerned that warmer weather could cause snowmelt to flood the area, endangering anyone who remained and potentially polluting nearby waterways with trash that has accumulated there.

Legal challenges to the pipeline remain pending. The line, which would carry oil from North Dakota more than 1,000 miles to Illinois, is largely completed. But one piece that crosses under Lake Oahe, a dammed section of the Missouri River that provides drinking water to the Standing Rock Sioux Reservation, has sparked months of protests and lawsuits from Native American tribes and advocacy groups.

Last week, the Standing Rock and Cheyenne River Sioux filed a motion asking a federal court to revoke the easement that the Army Corps had issued to allow Energy Transfer Partners to build the final stage of the pipeline under Lake Oahe. The motion argued that the Corps’ decision to issue the easement without undertaking an environmental impact statement was in violation of federal law and of the agency’s responsibility to protect the tribes’ treaty rights.

The judge is also expected to rule soon on a separate challenge by the Cheyenne River Sioux alleging that the pipeline could pollute water the tribe uses in religious ceremonies.

Energy Transfer Partners has been filing updates on the status of construction with the court. The latest, from Tuesday, said the company is working on a hole it drilled under the lake to ready it for the pipes. It said the pipeline could be ready to begin carrying oil within a few weeks.

In December, the Army Corps said it would conduct an environmental impact statement before allowing Energy Transfer Partners to complete the final section of the pipeline. Just days after taking office, however, President Donald Trump issued an executive order seeking to reverse that decision and calling for a speedy approval. The Corps issued the easement earlier this month.

Some protesters who cleared the site began gathering in neighboring camps on reservation land. Kandi Mossett, who has helped organize the protests with the Indigenous Environmental Network but who was not at the camp on Wednesday, said the activists would continue the fight with a march they are planning in Washington D.C. on March 10.

“It’s not just this community and just this pipeline that’s being impacted by the oil industry,” she said, noting that a large amount of North Dakota’s drilling is occurring on another Indian reservation in the northwestern part of the state, Fort Berthold. “It’s the big picture thinking that we’re trying to spread.”