Seven opponents of the Keystone XL pipeline chained themselves to a truck carrying pipe for the project until police came and arrested them. To get some of them loose, one of the truck’s bumpers had to be removed, according to activists there. Others attached themselves to the truck axle.

The demonstration in Livingston, Tex., was organized by a group called the Tar Sands Blockade, which on its Web site declared victory — for a day.

“Again, we witness the power of bringing together those battling corporate eminent domain abuse and those fighting to defend our natural commons from the unconscionable harm of surface mining and catastrophic climate change,” the group said. “Every day of delay is a victory.”

The group said that last week’s ruling by a judge in Lamar County, Tex., that TransCanada could use eminent domain to force landowners to allow the Keystone XL pipeline to cross their land left foes of the line little choice but to resort to civil disobedience. Four of the demonstrators — including a retired minister, a small businessman, a farmer and a woman who simply identified herself as “a grandmother” — posted videos explaining their position before attaching themselves to the truck.

“They are not going to endanger themselves or other people, but they will make their point consistently and effectively,” said Tom “Smitty” Smith, director of Texas Public Citizen.