However, respected members of the fire protection engineering community are beginning to raise red flags, and a resonating theory has emerged: The structural damage from the planes and the explosive ignition of jet fuel in themselves were not enough to bring down the towers. Rather, theory has it, the subsequent contents fires attacking the questionably fireproofed lightweight trusses and load-bearing columns directly caused the collapses in an alarmingly short time. Of course, in light of there being no real evidence thus far produced, this could remain just unexplored theory.