WestJet says one of its planes had just arrived in Toronto from Cancun Friday night when it was struck by a Sunwing aircraft, an incident that sparked flames and prompted an emergency evacuation on a freezing cold night.

WestJet says 168 guests and six crew were aboard flight WS2425 when it was struck by the Sunwing plane shortly after 6 p.m. According to WestJet, the Sunwing aircraft was pushing back from the gate.

Footage shot inside the WestJet plane shows passengers screaming and crying as flames erupt on the Sunwing plane.

Those aboard exited the WestJet plane on an emergency slide to frigid conditions outside. Toronto is under an extreme cold warning, with temperatures dropping to -21 C.

Sunwing said in a statement that no passengers or crew were on board its aircraft at the time or the collision, and that the incident occurred while the plane was “under tow.”

The airport confirmed to CTV News that the Sunwing aircraft was under tow when it made contact with the WestJet flight, and that fire crews extinguished a fire on the Sunwing plane.

Photos from the scene show extensive damage sustained to the tail of a Sunwing jet.

At least one person is being treated in hospital. An airport spokeswoman said a member of the Toronto Pearson Fire and Emergency Service sustained injuries.

A WestJet spokeswoman said there are unconfirmed reports of minor injuries. It’s unclear if any of those victims were hospitalized.

Passenger Adrianna Lobo called the incident “really scary,” especially since she was travelling with her children.

“When you see all the fire and the smoke and everybody standing, people didn’t know what to do,” she said.

Lobo said it wasn’t until she exited the plane that she was struck by the seriousness of the situation.

“I started crying because I realized what happened,” she said.

Another traveller said passengers didn’t initially understand what happened after the two planes collided, and a few even laughed.

“The plane rocked slightly, and we all looked out the window and we saw the (Sunwing) plane had backed up into us and had rammed their tail end directly into our wing, and it was all cracked and mangled and stuff. And everyone was kind of chuckling about it because it was just kind of crazy,” he said.

“And then suddenly it started spewing this steam. And then it set in that it’s not steam, it’s gas. And then the whole thing ignites and everyone starts panicking. It’s like chaos. Everyone is screaming, standing up. The flight attendants are shouting over a megaphone for everybody to calm down.”

The airport told CTV News that airport operations were not significantly affected, and that an investigation is being conducted by the Transportation Safety Board.

WestJet said it is in contact with the Transportation Safety Board, the GTAA and other groups responding to the incident.

Aviation expert Phyl Durdey said collisions between grounded planes are “pretty rare” because there are typically several crew members guiding an aircraft as it’s being towed.

“When an aircraft is getting pushed back there’s usually wing walkers, tail walkers, so there’s safety precautions in place,” Durdey told CTV News Channel. “Those guidelines might’ve been a little bit different because the aircraft didn’t have any passengers on board.”

Multiple eyewitnesses posted photos of the incident on Twitter.

Warning: the top video below contains strong language.

##BREAKING Two planes clipped wing & tail. Sunwing tail caught fire. A Westjet aircraft evacuated via slides. No injuries reported. Toronto Pearson Fire on scene. pic.twitter.com/iOTQlfwRwq — Tom Podolec (@TomPodolec) January 5, 2018

Update Westjet #WS2425 Boeing 737 from Cancun just arrived. Taxiing to gate. Wing appears to strike tail of Sunwing Boeing 737 being pushed (possibly empty).

Passengers in Westjet evacuated via slides. Toronto Pearson Fire extinguished fire. pic.twitter.com/GEmsMraGVq — Tom Podolec (@TomPodolec) January 6, 2018

@SunwingVacay plane caught fire beside our @WestJet plane as we were almost ready to leave!! #smellslikesmoke guess we won’t be leaving anytime soon ☹️ pic.twitter.com/6K4tuxpuHG — Lisa Nadalin (@LisaannArts) January 5, 2018