one is forced to note that NONE of the luggage on shown shows any sign of heat, melting, burning, or molecular/ physical change.
The visisble red bag would perhaps show such if it is synthetic and had been subject to combustive force.
Explosions can occur without being chemical or generating (significant) heat - consider a child's balloon or even something like a football (although, of course, the force from either of these would probably be insignificant in such circumstances).