A day after a jetliner flipped moments after landing in Toronto, what was left of the aircraft remained upside down on Tuesday, its right wing and tail sheared off and the wreckage blocking the two longest runways at Canada’s busiest airport.

Officials were still marveling that all 80 people on board Delta Air Lines Flight 4819 escaped death or life-threatening injuries after the jet made a rough landing and rolled over, grinding to a halt in a cloud of dense smoke, sparks and flame at Toronto Pearson International Airport.

“Every time you board a flight, you are greeted by flight attendants and by flight crew,” Deborah Flint, the president of the Greater Toronto Airports Authority, said at a news conference on Tuesday. “But we saw the most important role that they play in action yesterday. The crew of Delta Flight 4819 heroically led passengers to safety.”

As investigators from safety boards in Canada and the United States, as well as the regional jet’s manufacturer, began combing over the wreckage, there was no official word on what caused the crash. They are expected to look into a range of factors, according to aviation safety experts.

“Everything’s on the table: The wind, the pilot performance, the airplane, all those things will be looked at in detail,” said John Cox, a former airline pilot and founder of Safety Operating Systems, an aviation consulting firm.

The plane approached the runway Monday in windy conditions that former pilots described as challenging.

For the 80 people on board the flight from Minneapolis-St. Paul International Airport, the world lurched immediately after the wheels hit the ground. In the blink of an eye, passengers found themselves hanging upside down, still strapped to their seats as jet fuel ran down the windows, said Pete Carlson, one of the passengers.

“The absolute initial feeling is just, ‘Need to get out of this,’” Carlson told the Canadian Broadcasting Corp.

But after a horrific string of fatal aviation accidents over the past two months, this crash proved different.

The seat belts that passengers had strapped on to prepare for landing likely contributed to the lack of a more catastrophic outcome, aviation experts said. Flight attendants and passengers were then able to help each other out of the emergency exits and, with the assistance of firefighters, onto the snowy runway.

Delta said that 21 passengers had been transported to local hospitals after the crash. By Tuesday morning, all but two had been released, the airline said.

Dianna Ertl, the mother of one of the passengers, said that her son, Mitch Ertl, 37, had been treated at a hospital and would be returning home to Minnesota on Tuesday. He had been on a business trip.

“My heart sank,” said Dianna Ertl, describing the phone call she got from her son.

Mitch Ertl told her that he had been one of the last people to exit the plane, and that he had needed to break a meal tray table that was blocking him from unbuckling his seat belt, she said.

“I felt relieved that I was talking to him, that I knew he was walking,” Dianna Ertl said.

Video of crash

The crew of an air ambulance waiting to take off captured the moment of the crash-landing on video. The video, which spread on social media and was verified by the New York Times, may offer clues about what caused the plane to end up flipped over on its back.

Footage appeared to show the right landing gear touched down first, which is not unusual for an aircraft landing in blustery conditions, experts said. But the landing gear then appeared to give way, probably contributing to the right wing breaking off.

“Something broke that wing off right near the root,” said Ben Berman, a safety consultant who is also a former airline pilot and federal crash investigator.

The jet, a Bombardier CRJ900 operated by a Delta subsidiary, Endeavor Air, was landing at 2:15 p.m. Eastern time after a seemingly normal flight along the busy route between Minneapolis and Toronto.

“The second that the wheels hit the ground, then everything happened,” Pete Koukov, a professional skier from Colorado who was on the flight, said in an interview. “The next thing I know, we’re sideways.”

The plane skidded on its right side, said Koukov, who was sitting at a window seat on the opposite side. He saw sparks and flames as the plane hit the ground.

When the plane came to a stop belly-up, Koukov unbuckled his seat belt and lowered himself down to the ceiling of the aircraft — now the floor, he said. “People were panicking,” he said.

A video taken by Koukov shows a flight attendant helping passengers climb out of the plane, urging them to hurry and to leave their belongings behind.

Investigation continues

The Transportation Safety Board of Canada will lead the investigation into the crash, officials have said, with help from investigators from National Transportation Safety Board.

The crash is likely to create aviation chaos for days to come. Toronto Pearson was already juggling a slew of delays and cancellations caused by a series of winter storms that dropped 20 inches of snow on the airport.

Air Canada said in a statement Tuesday that it had canceled 1,290 flights over the past six days and that it would take several more days to return to normal operations.

Flint said that the wreck would likely remain on the runway for 48 hours.

Flint and the airport’s fire chief both declined to discuss possible causes of the crash, citing the investigation. The government’s weather service said that gusts of up to 38 mph were recorded as the plane was landing.

Investigators will probably closely evaluate parts recovered from the crash to understand whether they were faulty beforehand, experts said. And the plane’s black boxes — a cockpit voice recorder and flight data recorder, which have been sent to labs for analysis — will be crucial in explaining what happened, helping shed light on the force and angle at which the plane landed.

“I think that the flight data recorder will quickly determine whether or not this landing was quote-unquote hard,” said Jeff Guzzetti, a safety consultant and former investigator for the Federal Aviation Administration and the NTSB.

The crash provides some positive lessons, too.

The seat belts that passengers were required under Canadian law to wear during landing worked as intended, keeping them strapped in even as the plane rolled over. And so did the seats that were bolted to the aircraft’s structure and designed to withstand stresses of up to 16 times the force of gravity.

That the exit doors could still be opened underscored the construction quality of the plane, Cox said. And the ability of the crew to open those doors, even while upside down, and to get passengers out quickly, was a testament to their training.