— OKLAHOMA CITY (AP) — Eight people were arrested Monday at a construction site for the Keystone XL oil pipeline in central Oklahoma, including one man who locked himself to a crane-like piece of machinery, authorities said.

The two women and six men were arrested on trespassing complaints at the site near the town of Schoolton, Seminole County sheriff’s Chief Deputy Chris Conn said. One woman also was cited for resisting arrest. None of their names has been released.

“We had several individuals on private property who refused to leave, and they were arrested for trespassing,” Conn said. “One individual was chained to some equipment ... his wrists were chained together.”

The organizers, protesters from the Great Plains Tar Sands Resistance, cited environmental concerns and the oil extraction’s impact on indigenous people as the reason for their protest.

Calgary-based TransCanada has proposed a 1,700-mile pipeline, dubbed the Keystone XL, to carry oil derived from tar sands in Alberta to refineries along the Texas Gulf Coast. Although the northern leg of the project has not received federal approval, the company currently is constructing the 485-mile southern portion of the pipeline that will transport oil from storage facilities in Cushing, Okla., to Texas, said TransCanada spokesman David Dodson.

The man who locked himself to the machinery, called a side boom, was removed after he was lowered to the ground and a local fire department used a pair of bolt cutters to free him, Conn said. A spokesman for the environmental group identified the man as Stefan Warner, a youth pastor from Harrah.

Warner said in a statement that, “I figure folks have to take action to stop our beautiful Oklahoma from being marred by a foreign corporation, and stand up to fight big corporations who think that poisoning people and stealing land is acceptable so long as they make a profit.”

Environmental groups have been pressing President Barack Obama to reject the pipeline, saying it would carry “dirty oil” that contributes to global warming. But business and labor groups have urged approval of the project, saying it would provide much-needed jobs and encourage North American energy independence.

Dodson said Monday’s incident is the second in Oklahoma in recent weeks in which a protester was arrested after attaching themselves to a piece of equipment at a job site. He said a Norman woman was arrested last week after locking herself to a piece of machinery at a job site near Ada.