VANCOUVER — Canadian border agents found four guns and what they feared was an improvised explosive device in a car Tuesday night, prompting the temporary closure of the Peace Arch border crossing.

Officers closed the crossing, one the busiest portals between the United States and Canada, and evacuated six nearby houses while they investigated.

The RCMP explosives squad was summoned and determined a wired, tubular package found in the engine compartment of the car did not contain explosives.

The driver of the car was taken into custody for questioning. Surrey RCMP released a statement saying the suspect appeared to be suffering from a mental illness and his parents had been contacted in Oregon. No charges were anticipated.

"At this time, we don't believe that he had any malicious intent," said Cpl. Steven Han of the Surrey RCMP.

Canada Border Services Agency officers stopped the vehicle when it tried to cross into Canada.

The firearms - a 9-millimetre handgun, two shotguns and one rifle and rifle stock - were found in an initial inspection of the car, the RCMP said. The package was found a few moments later in the engine compartment.

Surrey RCMP and the Washington State Patrol near Blaine, Wash., diverted border traffic for more than two hours.

"The driver was interviewed by border services officers, who were suspicious," said Paula Shore, a spokeswoman for Canada Border services Agency. "We take safety and security very seriously.

"Our border services officers are trained to look for inconsistencies. It's never just one thing that makes them want to take another look at someone."