Air India's deadly plane crash that killed at least 270 people has triggered a wave of speculation about what led to the world's worst aviation disaster in a decade, but authorities are slowly narrowing down areas of investigation.

The London-bound Boeing 787 struck a medical college hostel when the plane crashed into a residential area of the northwestern city of Ahmedabad minutes after takeoff Thursday.

The crash of an Air India Boeing 787 Dreamliner seconds after takeoff from Ahmedabad city, killing all but one of the 242 people on board, is the world's worst aviation disaster in a decade. At least 30 people were also killed on the ground as the airliner crashed into a medical college hostel near the airport.