Five protesters were arrested late Tuesday morning while trying to block a ship from unloading pieces of oil pipe at the Port of Vancouver. The protesters arrived early in the morning in boats and positioned themselves in the Columbia River at the base of one of the port’s docks.

The ship, carrying pipe for the Trans Mountain Pipeline under construction in British Columbia, was in a secure spot away from port property and protected by the U.S. Coast Guard, according to Port of Vancouver spokeswoman Heather Stebbings.

“It’s an evolving situation,” Stebbings said at about 9:30 a.m. “Port operations have been affected.”

The Vancouver Police Department and Coast Guard were called in and began communicating with protesters from two local groups, Portland Rising Tide and Mosquito Fleet. Some of the protesters chained themselves to the dock, according to a news release. Others remained in kayaks and boats in the water. Stebbings estimated there were about 20 protesters in total.

Vancouver Police Department spokeswoman Kim Kapp said police initially announced that the protesters needed to disperse, then began making arrests when they failed to do so. The arrests took place between 11:30 a.m. and noon, Stebbings said.