CTV News Vancouver has learned that a massive shutdown at the airport on Sunday morning was due to a security software glitch, and not an apparent security breach.

At the time, the Canadian Air Transport Security Authority (CATSA) said there had been an alleged security breach -- involving an image in a piece of carry-on baggage.

After numerous calls, a CATSA representative told CTV News that an image of an explosive device, which turned up on a pre-boarding security X-ray, was actually a projection of a training image used to keep guards on their toes.

The training image had been erroneously activated in the software program, and CATSA still isn't sure how this happened.

Vancouver airport security guards saw a ghost image of an explosive device on their screens, but didn't realize it was part of the training system.

When they couldn't find a real bag associated with the image, they believed a passenger with a dangerous device might be headed for a plane, and ordered a complete shutdown of the airport.

"It was thought to be an explosive device," Renee Fairweather. "That's why the action had to be taken."

Airport traffic was halted for about two hours, and the cost of Sunday's delays is estimated to be in the $1 million range.

CATSA still isn't sure how the ghost image became activated on the Vancouver equipment. The national agency has been using this software program for three years.

"As a result of what happened Sunday, every piece of equipment that has that feature on it has had that feature deactivated... across the country," Fairweather said.

With a report by CTV Vancouver's Kate Corcoran