An eyewitness said two planes collided o the tarmac causing a fire on one and an emergency evacuation of the other.
The aircraft appear to have clipped wings causing one of the planes burst into a fireball forcing hundreds of passengers to evacuate.
WestJet and Sunning have confirmed that it was their jets involved in the collision at Toronto Pearson International.
Videos posted on social media seemed to show the tail of one of the planes alight and spewing black smoke.
The screams of terrified passengers were audible in the clips as they fled the plane.
Sunwing said that no passengers or crew were on board its aircraft at the time of the collision and the incident happened while the plane was “under tow”
WestJet tweeted: “WestJet has confirmed that WS2425, a Boeing 737-800 with 168 guests and six crew onboard, inbound from Cancun to Toronto Pearson, while waiting to proceed to the gate and stationary, was struck by a Sunwing aircraft pushing back from the gate.
“Due to the position of the aircraft on the laneway, WestJet guests required evacuation via emergency slide.
“Emergency crews were on hand and responded immediately.
“We can confirm guests are safely in the terminal and they are in the process of clearing customs.”
Sunwing posted a statement on Facebook, writing: “A Sunwing aircraft, under tow by our ground handling service provider, came into contact with another aircraft. There were no Sunwing crew or passengers onboard at the time of the incident.”
There were 168 passengers and six crew members on board the flight WS2425, but only a few passengers suffered minor injuries.
One of the fire crews was seriously hurt in the incident and rushed to hospital.
Many flights in and out of the airport have been disrupted by the collision.