Does this sound planned to you - it does to me.
From what I heard, the minute the bus went through window the looters were in there - one lady who described it says she was pushed aside almost as soon as the bus crashed.
The reason I say this is that it doesn't match my belief in human nature. Sure there are are people who will loot but I still think most will stop and consider it before acting. So in my mind, yes there might be a mob reaction, but it would grow more slowly as people see the first person act and then stop to consider the moral and risk implications before joining in.
The way it described it sounded like there were a load of people ready to loot standing by the shop.
Cheers,
Nigel