SpaceX has traced the likely cause of the explosion that destroyed its Starship vehicle during its Jan. 16 test flight to a leak of liquid oxygen or liquid methane.

SpaceX launched Starship on Thursday for a seventh test flight, after weather concerns pushed back an experiment that will feature the spacecraft’s first payload deployment test, and while it successfully caught the Super Heavy Booster, Starship lost connection and “experienced a rapid unscheduled disassembly.”

Witnesses spotted debris from a SpaceX Starship after the spacecraft exploded midair following a test flight from south Texas.