A Delta Air Lines passenger plane has flipped upon landing at Toronto Pearson Airport amid heavy wind and snow.
Survivors were seen walking from the wreckage, shielding their faces from strong wind gusts.
Here's what we know about the incident.
What happened?
Delta flight 4819 took off at 11:47am local time from Minneapolis, Minnesota, and flew at 29,000 feet en route to Toronto Pearson Airport.
As it turned to approach runway 23 at the airport at about 2:15pm local time, the air traffic control tower warned pilots of a possible airflow "bump" in the glide path from an aircraft in front of it.
There were no further conversations with the Delta flight until the tower confirmed that a plane had overturned on landing amid windy weather following a snowstorm.
Pete Koukov, a passenger on the plane, told CNN he didn't know "anything was the matter" until they hit the ground.
"We hit the ground, and we were sideways, and then we were upside down hanging like bats," Mr Koukov said.
"Just feeling lucky and happy I got to give the person I didn't know sitting next to me a big hug, that we were OK."
Video shows passengers walking away from the plane, which is missing its tail and at least one wing.
The cause of the crash is still unknown.
How many people were on the plane?
There were 80 people on board the plane — four of them were crew members.
In a press conference, Toronto Pearson President Deborah Flint said there were 22 Canadians among the passengers.
How many people were injured?
At least 18 people on board the plane were injured, according to Peel Regional Paramedic Services.
Three have been taken to hospital in critical condition: a child, a man in his 60s and a woman in her 40s.
None of their injuries were considered life-threatening.
The airline said there were no fatalities.
"Several customers with injuries were transported to area hospitals. Our primary focus is taking care of those impacted," Delta said in a statement.
Ms Flint also said there was "no loss of life and this is indeed a part to our heroic and trained professionals, our first responders at the airport".
She said emergency workers at the airport "mounted a textbook response". They reached the crash quickly and evacuated everyone from the plane.
How does a plane flip without any casualties?
Aviation expert Keith Tonkin said the fact that all people on board the aircraft were evacuated alive was "cause for cautious relief".
"I expect that the requirement for passengers to have their seatbelts on during landing will have been a significant contributor to this outcome," Mr Tonkin said.
John Cox, the chief executive of aviation safety consulting firm Safety Operating Systems, said to see a plane resting upside down was very rare.
"We've seen a couple of cases of take-offs where aircraft have ended up inverted, but it's pretty rare," he said.
What caused the Delta plane to flip?
It's too early to say what caused the plane to flip but experts say the weather may have played a factor.
Conditions at the airport were icy, windy and freezing after a snowstorm blew through the north-east of the continent over the weekend.
According to the Meteorological Service of Canada, the airport was experiencing blowing snow and winds of 27 to 35 knots, which is about 60 kilometres an hour.
The temperature was about 16.5 degrees Fahrenheit (-8.6 Celsius).
"It's not clear exactly how the aircraft ended up flipping on its back, but it appears that the snowy, windy conditions could have impacted on the ability of the flying pilot to maintain directional control during the landing," Mr Tonkin said.
Speaking at a brief news conference, Toronto Airport fire chief Todd Aitken said the runway was dry.
"What we can say is the runway was dry and there was no crosswind conditions," Mr Aitken said.
But Mr Cox, who had seen videos of the incident, pushed back against the suggestion there were no crosswinds.
He said there was an average crosswind of 19 knots (35kph) from the right as it was landing, but he noted this was an average, and gusts would go up and down.
"It's gusty so they [pilots] are constantly going to have to be making adjustments in the air speed, adjustments in the vertical profile and adjustments in the lateral profile."
There was also the question of why the plane was missing its right wing.
"If one wing is missing, it's going to have a tendency to roll over," Mr Cox said.
"Those are going to be central questions as to what happened to the wing, the flight data recorder and cockpit voice recorder."
Before the crash, the airport had posted a photo of the runway as ground staff cleaned up following the storm.
"Our crews worked all weekend to keep the roughly 5 million square meters of airfield clear of snow to keep planes arriving and departing safely," it said on X.
Where did the crash occur?
[map]What type of plane crashed at Pearson?
A Bombardier CRJ-900 aircraft.
The plane is owned by Endeavor Air, a subsidiary of Delta Air Lines.
It's the same family of aircraft as the CRJ-700, the type of plane involved in the midair collision near Ronald Reagan National Airport in Washington DC last month.
What happens now?
Investigations into the incident are ongoing.
The Transportation Safety Board of Canada will lead the investigation.
The US National Transportation Safety Board will send a team of investigators to assist.
ABC/wires
