A Germanwings plane traveling from Barcelona, Spain to Dusseldorf, Germany crashed in southern France on Tuesday, leaving no expected survivors. 

The exact cause of the crash has not been confirmed as of Wednesday morning, but here is what we know so far: 
-After reaching its cruising altitude of 38,000 feet, the Airbus A320 descended for eight minutes before colliding with a remote mountainside in the French Alps. 

-There is no evidence that the pilot sent out a distress signal or attempted to contact air traffic control. 

-The plane did not veer off course during the descent, indicating that the pilot did not immediately lose control over the plane. 

-One leading theory, according to CNN, is that a sudden loss of cabin pressure prompted the pilots to descend to a lower altitude, but that they were incapacitated by the lack of oxygen before being able to follow through with the emergency maneuver. 

-The flight manifest included passengers from at least 15 countries, including two Americans. 

-Both of the plane's black boxes have been located, though one was badly destroyed and missing a memory card, and no valuable data has yet been retrieved from the other. 

-An investigation into the crash is still underway and is expected to last several weeks.