An official report on the world’s deadliest aviation accident in a decade, seen by CNN, has answered one key question – but raised others.

The Air India airliner carrying 230 passengers and 12 crew members was on its way to the United Kingdom when it crashed into a building shortly after takeoff on June 12, killing all aboard, except for one survivor, and several people on the ground, according to authorities.

One month after an Air India flight crashed and killed over 200 people, investigators on Saturday revealed the fuel to both engines of the Boeing 787 plane had been mysteriously cut off prior to the incident.