Let’s be clear.
OXYGEN neither burns nor explodes. Ever.
Oxygen is the oxidizer (duh) in a fire like this.
Compressed flammable gasses are the fuel here, as well as initially likely the fuel of the truck and the bus it ran into.
REM: I am a former firefighter.
Google BLEVE and Class B fires.
Of course oxygen doesn’t burn, BUT it increases the burn rate of any fuel by logarithmic numbers......
Just use a leaf blower on a leaf fire, and you’ll see an example. You’re adding oxygen, not fuel.
Oxygen is part of the combustion process, and to make any fuel burn faster - add oxygen. Adding oxygen will increase the burn rate many times more than adding fuel.
So, these could have been oxygen cylinders.