The three travellers arrested at the Sumas border crossing with an inert grenade have been released without charges.

But customs officials have derailed their travel plans: The trio, who were seeking entry into Canada to get to Alaska, have been returned to the U.S.

The Abbotsford, B.C., border crossing was shut down Thursday after agents with the Canadian Border Services Agency spotted a “dangerous-looking item” in a cube van during a secondary inspection around 2:45 p.m.

The grenade turned out to be inactive, but the border crossing was shut down while an Explosives Disposal Unit investigated. Abbotsford police were also called in to assist.

Staff Sgt. Rick Stewart of the APD sent a tweet around 6:30 p.m. revealing the people responsible for the kerfuffle had made no apparent effort to conceal the grenade.

“Cutting through BC? Don’t have grenade in plain view,” Stewart said. “No entry for u.”

A number of military-style bags labelled “zombies” were also found during the inspection.

Canadian Border Services says it took appropriate precautions.

“We do take all threats seriously at all of the border points -- and ensuring the public is safe in all of these situations and everyone in the immediate area as well,” said operations chief Ryan Vanderstar.