Passengers recall hanging upside down after Delta Air Lines plane ...

The Delta Air Lines flight flipped onto its back, injuring 18 people, after touching down during icy weather at Pearson International Airport in Toronto today.

US man Pete Carlson was on board and told CBC News anchor Adrienne Arsenault it was "really amazing" he and his fellow passengers were alive.

"Everything just kind of went sideways," Carlson recalled.

"One minute you're landing, kind of waiting to see your friends and your people, and the next minute you're physically upside down."

Carlson said he was left with only a cut on the top of his head after escaping the overturned plane.

Pete Koukov, 28, a professional skier from Colorado, told the New York Times the flight seemed normal up until the final descent.

The second that the wheels hit the ground, then everything happened," he said.

"The next thing I know, we're sideways."

Koukov was in a window seat and had a front-row view of the plane as it caught fire.

"So you look down and you see sparks and flames on the side that's touching the ground," he added. 

"We ended up completely upside-down. I unbuckled pretty fast and kind of lowered myself to the floor, which was the ceiling. People were panicking."

Koukov shared footage of his escape from the plane on Instagram. In it, flight crew can be heard telling passengers to "drop everything".

"Oh my god, I was just on this f----ing plane," he said.

Fellow passenger Todd Nelson told local media he saw a "big fireball" on the left side of the plane after the crash.

"When we hit, it was just super hard, it hit the ground, and the plane went sideways," Nelson said.

"Delta Air Lines Flight 4819, operated by Endeavor Air, crashed while landing at Toronto Pearson International Airport in Canada around 2.45pm local time," the airport said in a statement, noting the aircraft had departed from Minneapolis/St Paul International Airport.

In a statement, Delta Airlines confirmed that the aircraft was carrying 80 people.

"The flight was carrying a total of 80 people – 76 passengers and four crew."

The critically injured include one child and two adults.

It is too early to say what caused the plane to flip but weather may have played a factor.

According to the Meteorological Service of Canada, the airport was experiencing blowing snow and winds of 51km/h gusting to 65km/h.

The temperature was about -8 degrees.