A practical joke played on a Bellingham man by his co-workers in Olympia ended up closing the Lynden-Aldergrove border crossing into British Columbia for more than 3 hours yesterday as Canadian authorities investigated the possibility the man was carrying a bomb.

The 42-year-old man was stopped at the Canadian border, north of Lynden, around 4:40 p.m., Cpl. Dale Carr of the Royal Canadian Mounted Police (RCMP) said in a news release. During an inspection of his vehicle, "a crude device thought to be an explosive" was found under a seat, he said.

The inspection area and a duty-free shop were immediately evacuated, said Paula Shore, a spokeswoman for the Canadian Border Services Agency. The RCMP closed southbound Highway 13 to the Aldergrove crossing; at Canada's request, U.S. officials closed their side of the border to vehicles going north on Highway 539, diverting travelers to border crossings in Blaine and Sumas, she said.

By 7:30 p.m., the RCMP's bomb squad had arrived to investigate the suspicious device, Shore said.

Investigators later determined it was harmless, Carr said. Turns out, the man's co-workers in Olympia put some ball bearings into a metal tube and crimped the ends; they placed it in the man's vehicle to annoy him, with the idea "it would create a rattle that the driver would find difficult to locate," he said.

After being questioned, the man was released and will not face charges, Carr said.

Shore said the man may have been driving a company vehicle but couldn't say how investigators concluded he was the victim of a hoax. "It's not a good idea to play practical jokes at the border," said Shore, her tone making it clear she was not amused. The border reopened around 8:30 p.m.

As for the co-workers, Shore said it will be up to U.S. authorities to decide whether they should face charges because Canada does not have jurisdiction in the state.

A year ago, the border crossing at Blaine was closed for about an hour after a woman from Texas mistakenly drove to Vancouver, B.C., instead of Vancouver, Wash., with a grenade in her car. Canadian officials at the time said it was likely her military husband, who was based at Fort Lewis, accidentally left the functioning grenade in the vehicle's glove box. She was not arrested.

Sara Jean Green: 206-515-5654 or sgreen@seattletimes.com