Investigators found fragments that appear to bolster the theory that an oxygen tank exploded on a Qantas jet, forcing it to make a dramatic emergency landing with a car-size hole in its fuselage, an official said July 28.

Neville Blyth, a senior investigator from the Australian Transport Safety Bureau, said a valve and other small fragments would be tested to determine if they came from the tank, which is designed to provide oxygen to passengers during an emergency.

The plane had to make an emergency landing after a quick descent from 8,800 meters July 25. The 365 people on board, who heard a bang before the plane depressurized, were not injured.