A Greenpeace protester peers out from a barricaded van outside the Vancouver office of Enbridge. A Greenpeace protester peers out from a barricaded van outside the Vancouver office of Enbridge. (Steve Lus/CBC)

Four Greenpeace protesters who chained themselves in the Vancouver office of the Enbridge pipeline company have been arrested and released by police.

The protesters had locked themselves in the sixth-floor Burrard Street office of the company on Wednesday morning to draw attention to the company's plan to build a crude oil pipeline from Alberta to the West Coast of B.C.

Police moved in to remove them just before 1 a.m. PT Thursday, arresting the three women and one man, who ranged in age from 26 to 31.

Police say charges of mischief and assault by trespass are now pending against the four. Two other protesters remain locked in a van outside the office.

Oil spill spurs protest

The protesters say a recent oil spill from an Enbridge pipeline in Michigan illustrates the dangers of transporting oil by pipelines.

Greenpeace protesters created a mock pipeline oil spill outside the Vancouver office of Enbridge on Wednesday morning. Greenpeace protesters created a mock pipeline oil spill outside the Vancouver office of Enbridge on Wednesday morning. (Robert Zimmerman/CBC)

The Northern Gateway pipeline planned for B.C. has not yet been approved and Enbridge spokesman Alan Roth says new technology has made pipelines safer.

"An oil spill is definitely not inevitable. I know right now public emotion runs high, given recent events. But as I have said, pipelines have been statistically proven as a very safe way to transport petroleum products and the likelihood of a spill is extremely remote," said Roth.

Michigan's governor criticized Enbridge for not doing enough to clean up the spill in the Kalamazoo River on Wednesday, the same day the company reported making second-quarter profits of $232 million.