Updated at 3:55 p.m.

About 20 demonstrators who spent the better part of the morning blocking railroad tracks in Vancouver to protest oil trains were arrested Saturday after ignoring repeated orders to clear out, organizers and police said.

A coalition calling itself the Fossil Fuel Resistance Network organized Saturday's demonstration near the BNSF Railway and Amtrak Station in response to an oil train derailment across the river in Oregon that spilled thousands of gallons of crude earlier this month. Vancouver also is the site of a proposed, and highly controversial, $210 million oil terminal.

The alliance, comprising groups throughout the Northwest, says its aim is to end fossil fuel extraction and transportation.

Officers told the group to disperse dozens of times.

"You are trespassing on BNSF Railway property," an officer said over a loud speaker. "If you refuse to leave, you will be arrested for criminal trespass in the second degree."

But protesters, who alternated between singing and chanting, responded by turning up the volume.

"Want to know what all the fuss is? Rising up for climate justice," they chanted.

On June 3, a Union Pacific train derailed near the Columbia River Gorge town of Mosier, spilling 42,000 gallons of crude and sending up a massive plume of black smoke that could be seen miles away. No one was injured, but the crash damaged the city's sewage treatment plant and forced nearly 300 people to evacuate their homes.

It also prompted Oregon to ask the Federal Railroad Administration to place an open-ended moratorium on oil trains traveling through the state.

Sharon Rickman, 58, was among several dozen people who showed up Saturday. She says she's worried about "explosive oil," especially as the anniversary of one of the deadliest oil train crashes draws near. Forty-seven people were killed in July 2013 when an unmanned Montreal, Maine & Atlantic Railway train jumped the track in Lac-Megantic, Quebec.

"They're unsafe, they'll never be safe," she said.

She's also concerned about a proposed oil terminal in Vancouver. If Tesoro Corp. and Savage Services build the facility, it would be the largest in the Pacific Northwest, capable of moving 15 million gallons of oil through the Columbia River Gorge in four trains each day.

Rickman says communities should be moving away from fossil fuels and focusing on building greener economies.

She showed up Saturday to protest, not to get arrested. About 20 others, however, were fine with both.

BNSF police officers first issued trespass warnings to 19 people, seated in a circle and blocking the tracks. A BNSF train, which had been resting farther down in the rail yard, approached with its horn blaring. It stopped just shy of the rail crossing, about 50 feet from the protesters.

Some, including Mia Reback, weren't OK with that.

"BNSF bringing a train this close to protesters further shows they do not care about the health and safety of community members," Reback said.

Gus Melonas, spokesman for BNSF Railway, said no one was in danger. The train, which was loaded with paper products, was traveling about 3 mph and stopped outside the rail crossing, he said.

"We don't want anyone to get hurt," he said. "We will not run trains until it's determined to be safe for the public."

Melonas said BNSF was still assessing the affect of the protest, but said five trains had been waiting to get by. Train traffic on the main line first was blocked around 9:30 a.m.

At the protest's peak, Reback said, about 100 people showed up. They held umbrellas, decorated with sunflowers, and posters and banners, including one that read, "BAN the BOMB TRAINS."

Reback believes such protests will help keep the community safe.

She looked around at the group, kept back, just off the tracks by police officers, while the others were arrested.

"It's beautiful," she said.

Officers, from BNSF, Vancouver and the Clark County Sheriff's Office, arrested about 20 protesters on second-degree criminal trespass accusations and loaded them into vans to be taken to the Clark County Jail, according to police and protest organizers. As police took each protester away, their supporters standing nearby chanted their names.

At one point, officers in riot gear showed up, but they stayed back.

By 1 p.m., the tracks were cleared. The waiting train traveled through, its horn again blaring.

-- Rebecca Woolington

rwoolington@oregonian.com

503-294-4049; @rwoolington