The police don’t *have* sidearms. They could caution them to desist from their activities, though. In a respectful way that observes the miscreant’s dignity.
Well, I would say that facing off against mobs of thugs with machetes requires a visit to the armory before heading out to the streets! These bastards are not going to respond to “harsh looks” and oral warnings from the constabulary. How far are the police going to let this go? Are they going to let this continue up to the point that the gangs approach Buckingham Palace???
“Stop! or I’ll say stop again!”