The Mounties say half of all guns used in gang shootings in B.C. have been smuggled into Canada from the U.S., usually Washington state.

But with four million cars crossing through Peace Arch every year, it's impossible to check every one. Last year alone, 191 guns were seized at B.C. crossings.

Derek Collins, the chief of operations at the Port of Douglas, says most are guns that smugglers go to great lengths to bring into the province.

Showing off a clean back seat of an SUV, Collins uses a detector dog to check the vehicle.

The canine immediately smells trouble and starts digging at the bottom of the SUV. He finds something right away and sits down.

"The dog sitting down is an indicator some odor has been detected that he's been trained to find," says Collins.

Under the speakers are some strange wires that are not connected to anything. But once a power source is connected to them a hidden compartment opens up in the back.

"And inside we find smuggled handguns," says Collins.

The owner of the vehicle was charged, but most gun smugglers aren't.

Collins says that's changing.

"I would say the charges that our criminal investigations is increasingly laying more charges," he says.

"The sophistication of the concealment method, the intent, the purpose of the trip in Canada, the statements that were made prior to the discovery -- the type of weapon that it is. They all play into the decision to lay charges or not."

Smugglers are more often fined or barred from Canada for awhile. But many get away with it.

"We know they have been smuggled when we find them in the hands of criminals in a drive-by shooting or homicide," says RCMP spokesperson Tim Shields. "We have a very long border -- in places it is easy to smuggle contraband across that border."

Guns get in because not every car is searched. Keeping them out relies on the instinct of the people in the booth, and it's not always easy to tell which car has a secret.

With a report from CTV British Columbia's Shannon Paterson