We don't need guns - we just need more people like those store owners - i.e. actual communities that stand up for each other.
If people were like that everywhere - and if the Met weren't apparently so slow and useless - this probably wouldn't have gone as far and for so long as it has done.
If looters are constantly turned away from being able to loot, they'll eventually get bored, but every time they're successful it empowers them to keep going, and potentially get do more severe things.