Aviation experts are calling the sudden engine fuel cutoff on an Air India jetliner “absolutely bizarre.” A preliminary report into the crash that killed at least 260 people does not clarify how the fuel control switches were turned off.

A report released by India's Aircraft Accident Investigation Bureau pointed to fuel switches that flipped off during takeoff, depriving engines of power.

The US aviation regulator has said fuel control switches in Boeing aeroplanes are safe, following their reported involvement in a fatal Air India crash that killed 260 people in June. The safety of the switches has become a key point of concern after a preliminary report on the disaster was released by investigators on Friday.