Eight international flights were delayed for hours at Pearson International Airport after a passenger went through security without declaring an item.
Beacause of the breach, Transport Canada decided to re-screen everyone who had gone through security around 11 p.m.
Some passengers standing in the long security line-ups were frustrated after being forced to get off planes they had just boarded, but others told the media they felt safer knowing the airport security was tight.
All eight flights were in the air by 3 a.m., and the incident didn't affect any travelers later on Sunday.
The incident came a week after the airport increased security in response to a flaming SUV that drove into a Scotland airport terminal building's entrance.
A spokesman for the Greater Toronto Airports Authority said Pearson was reviewing procedures after the alleged terror attack at Glasgow Airport.