I`m with Steve, Cirrus and Flow. This demonstrates just how ineffective a light aircraft is as a weapon of destruction whether it be accidental or intentional and there is no need to restrict GA. Admittedly, were the aircraft especially prepared the results could be more serious but probably not all that much and that is a terrorist operation and cannot be controlled by saying `you must not do it.` I`m not giving away any secrets by saying that a truck would be much more effective and much easier to obtain and use.
Mike W