[Bob]

...like locking down the store while these hoodlums go about their "business", which means they'd have to put in smash-proof glass so these feral animals can't get out - that should hold them until the police arrive.

Unfortunately, doing that would also lock down any employees who were in the store at the time. I have to wonder if that's such a good idea. Some method would need to be devised to keep the store's employees from coming to harm.

[UCANSEE2]

Some method would need to be devised to keep the store's employees from coming to harm.

Provide them with firearms training, practice, a pistol and bullets.