Passengers travelling to the US at Toronto's Pearson International Airport are cautitioned to check the status of their flights and expect some delays as numerous flights were cancelled last night after a fire in Terminal 1.

This morning around 3am, the airport announced on Twitter that both Terminals 1 and 3 are operating normally, with the exception of Terminal 1 departures to the United States, where some delays may be experienced.

Fire crews responded at about 6:30pm ET Sunday. A photo on Twitter from Rosa Hwang showed the inside of the terminal with smoke.

At least one traveller who was held on the tarmac for about three hours during the ordeal after arriving from Panama, said their Rouge pilot was great at communicating what was happening.

Heather Greenwood Davis told TravelPulse Canada, “The pilot was amazing about sharing information approximately every 15 minutes. We travel carry-on only and have nexus so we were less than 20 minutes from airport door to the ParknFly van. The baggage area is a zoo. I can’t imagine most people will leave with their bags tonight. And though people were tired, people were generally patient and good on our flight.”

She added passengers were also helpful, as a fellow passenger told her "there were a lot of little kids off her flight from the Dominican Republic and in that instance, parents set up a makeshift Paw Patrol watching station while they waited."

Peel police said on Twitter they had received no reports of serious injuries, although paramedics treated “a few patients” for smoke-related injuries and at least one person was sent to hospital.

No word yet on cause and police have said there has been no indication the fire was suspicious.