As it landed in the Canadian city, the plane skidded along the runway in flames before flipping over and coming to a halt upside down. Passengers described their amazement as most of them walked away without injuries.

It remains unclear what caused the incident, which is under investigation.

There were 76 passengers and four crew on the flight, which had travelled from the US city of Minneapolis before making its crash-landing in Canada.

A spokesperson for Delta said the money offer had no strings attached and did not affect customers’ rights.

The plane crew and emergency responders were praised for their quick work in removing people from the wrecked vehicle. The plane’s various safety features have also been credited for ensuring no loss of life.

All but one of the 21 passengers who were taken to hospital had been released by Wednesday morning, the airline said.

Delta’s chief told BBC’s US partner CBS News that the flight crew were experienced and trained for any condition.

The airline’s head Ed Bastian told CBS the plane crew had “performed heroically, but also as expected”, given that “safety is embedded into our system”. He said Delta was continuing to support those affected.

Several theories about what caused the crash have been suggested to the BBC by experts who reviewed footage, including that harsh winter weather and a rapid rate of descent played a role.

One passenger recalled “a very forceful event”, and the sound of “concrete and metal” at the moment of impact. Another said passengers were left hanging upside down in their seats “like bats”.

The cockpit voice recorder and flight data recorder have been recovered from the wreckage. The investigation is being led by Canada’s Transportation Safety Board (TSB), supported by US officials.

The accident was the fourth major air incident in North America in a space of three weeks – and was followed on Wednesday by a crash in Arizona in which two people lost their lives when their small planes collided.

Experts continue to insist that air travel is overwhelmingly safe – more so than other forms of transport, in fact.

That message was emphasised by US Secretary of Transportation Sean Duffy, who told CBS on Wednesday there was no pattern behind the incidents, each of which he said was “very unique”.

Airport CEO Deborah Flint said investigators will be reviewing the aircraft on the runway for the next 48 hours, adding that this was “not the time” to speculate on the cause of the crash.

The Delta Air Lines flight from Minneapolis skidded along the runway with flames visible before it came to a halt upside down.

Twenty-one people were injured, of which 19 have been released from the hospital, authorities said on Tuesday. The two patients do not face life-threatening injuries.

There were 76 passengers and four crew on board the 16-year-old CRJ900 aircraft, made by Canada’s Bombardier company.

Injuries at the time of the crash ranged from head injuries to back sprains, and nausea and vomiting due to jet fuel exposure, a representative for Peel Regional Paramedic Services said.

Experts told the BBC it was miraculous that everyone survived the crash, adding that the swift response of flight attendants and emergency crews helped save people, as well as plane safety improvements.

Passengers on board said they were hanging upside down in their seats and had to release themselves, falling on to the ceiling before clambering out on to the snow-covered tarmac. Firefighters quickly came to the rescue.

“We were upside down hanging like bats,” passenger Peter Koukov told CNN.

A child was among the injured but was in good condition as of Tuesday morning, the Hospital for Sick Children in Toronto told the BBC’s US partner CBS News.

Although the airport had been experiencing “extreme” weather conditions, Monday was categorised as a “clear day” for operational recovery following prior disruption, officials said.

Two runways remained closed on Tuesday as the Transportation Safety Board of Canada continued its investigation into the crash.

Toronto was hit by a major snow storm over the weekend, but authorities said the runway was dry at the time of landing and that there were no cross-wind conditions.

Cross-wind conditions refer to when wind blows opposite to the direction of travel which could affect vehicles and aircraft by pushing them sideways and requiring corrective action to maintain control.

Before the crash, authorities said snow had stopped and “frigid temperatures and high winds [were] moving in”.

Audio recording from Pearson’s air traffic control tower, reported on by the Canadian Press, shows the flight was cleared to land shortly after 14:00 on Monday, and that the tower had warned the pilots of a possible air flow “bump” in the glide path from a plane in front of it.

Analysts say it is possible the plane may have struck an item on the runway such as a light when it landed.

The crash is at least the fourth major aviation incident in North America in the past month, including an American Airlines plane in Washington, DC, that collided with a US Army helicopter, killing all 67 people on board.

Ms Dali, whose identity was confirmed by CBS, boarded a Delta Airlines flight last week from New York’s JFK airport to Charles de Gaulle Airport in Paris without a boarding pass.

She was taken into custody upon arrival in France.

French National Police said the woman is of Russian nationality and was refused entry to France because she had no visa. She has not been charged.

Ms Dali was able to get through an advanced imaging technology body scanner at JFK airport, and dodge document and ID checks during the security process.

In a statement provided to CBS, a TSA spokesperson confirmed that “an individual without a boarding pass was physically screened without any prohibited items. The individual bypassed two identity verification and boarding status stations and boarded the aircraft.”

But it remains unclear how she was able to get through and board the plane.

“Nothing is of greater importance than matters of safety and security,” Delta said in a statement. “That’s why Delta is conducting an exhaustive investigation of what may have occurred and will work collaboratively with other aviation stakeholders and law enforcement to that end.”

The Guardian reported that once on board, Ms Dali moved from one bathroom to another and never took a seat – until flight attendants began to notice.

A social media video posted by a passenger shows the moment a captain explained to the plane that officials were coming to remove the woman.

“Folks, this is the captain, we are just waiting for the police to come on board,” he said in the video. “They may be here now and they directed us to keep everyone on the airplane until we sort out the extra passenger that’s on the plane.

“A man on the flight shared mobile phone video with CNN of the woman, who remains in France, allegedly making a disturbance on another flight that was set to return her to New York.

He said she repeated: “I do not want to go back to the USA. Only a judge can make me go back to the USA”.