Now here is me thinking that oxygen is not flammable, it just supports whatever is burning and makes things burn hotter and faster when there is lots of it. So if I am correct, there must have been an ignition source (root cause) and/or a fire, which rapidly accelerated in the oxygen rich environment. Wonder what that was? I think therefore the oxygen leak was not the cause of the fire but was the accelerant.
Standing by to be corrected.