Even though the fuel is diesel, the M113 will burn. Hit a mine, take an RPG hit, or rupture an oil or fuel line and you have your basic fire. And once it starts to burn the padding, troop equipment and any ammo on board goes too.
While working east of Khe Sanh, 28 April 1969, this C Co track hit a mine. The crew was able to evacuate the wounded, remove much of the equipment and ammo but even after the main fire extinguisher discharged there was still open flame.
The vehicle was a total loss.