It's better to have a gun and not need it than, etc.Depends. If emergency caller states guns involved, armed units are of course sent, not normal police. If normal police arrive as a routine call and suddenly guns appear, they will back off (a bit), seal exits and routes and call in armed units. Normal police in the UK are now routinely armed with 50000v tasers.
In Lee Rigby’s case (and it looks as if callers DIDNT mention the gun, just that he’d been stabbed), the normal police arrived in 3mins, the armed in 9 minutes, after the former called for armed support.
It's better to have a gun and not need it than, etc.Yeesh.