A Delta Air Lines flight from Minneapolis crashed, turned upside down and caught fire on the runway at Toronto Pearson International Airport while attempting to land Monday, the latest in a string of passenger plane crashes since December.

The crash of a passenger jet that flipped while landing in Toronto is raising questions about the cause of the accident.

An investigation is underway into the Delta plane that crash-landed Monday in Toronto. What caused it remains to be seen, but here's what we know so far.