All departing flights from Pearson International's Terminal 1, were suspended while police searched for a male passenger who breached airport security.
The man walked through security without being checked around 10:45 Wednesday evening.
Cst. Lillian Fitzpatrick with Peel police told Newstalk 1010, they have a photograph of the passenger continued searching for him, but he was not found to be on domestic flights.
Passengers who landed, were kept on board aircraft until police finish their search.
Cst. Fitzpatrick says the man had boarded a connecting flight at Pearson to Sao Paulo, Brazil and he had shown his boarding pass and passport at the gate before boarding the Air Canada flight.
That flight had taken off before police were ever made aware of the security breach.
The constable says the matter is now in the hands of Air Canada and there was no threat to public safety.
Pearson Airport tweeted that domestic departures would resume shortly, around 12:30 a.m. Everything was back to normal as of 12:45 a.m.