Well, I am sorry that policing in your area is poor... But perhaps an actual crime in progress would elicit a different response.

I have called the police twice in recent years, once for a road traffic accident in my street and once for road rage and they showed up in under 5 minutes (UK). It's not possible to generalise, but I suspect that a report of an assault in progress should get a quick response (maybe don't mention the water guns too much ;) )