Why did the Delta plane crash and flip in Toronto? Here’s what we know about the cause. [Video]

A Delta Air Lines jet crashed Monday during a fiery landing at Toronto Pearson International Airport, skidding down the tarmac before coming to a stop while flipped upside down. 

The dramatic scene, captured on video by air traffic controllers and, later, the passengers on board, left 21 people injured — two critically. What caused it remains under investigation by the Canadian Transportation Safety Board and multiple transit agencies in the United States. Here’s what we know so far.

The ceiling of the plane “had become the floor”

Delta Air Lines Flight 4819 departed Minneapolis-St. Paul International Airport in Minnesota on Monday morning, carrying 76 passengers and four crew members. 

The plane, operated by Minneapolis-based Delta Air Lines subsidiary Endeavor Air, struck the landing strip as it arrived at Toronto Airport at about 1:15 p.m. CST, according to Delta. Images and video of the accident showed the CRJ-900 aircraft catch fire when it hit the pavement and proceeded to turn sideways while sliding across the airfield, losing its tail and both …