I wouldn;t want to bother the police, I have to say. But your idea of telling these people (assuming they;re actually still there of course, and not completely barking. no hang on, they are fairly likely to be barking. But if they don;t look dangerously so, then) - telling them it will be a Very Bad Idea to offend the very entities they're there to see - I reckon that;s an excellent strategy.