Look at Norco, North Hollywood, any number of similar incidents from the 1980s and 1990s. How would you suggest such incidents that played a huge role in the tacticalization of police be dealt with? No groups of armed citizens turned out to assist. The police were outgunned -and unsupported.
You are seeing and living the results of why.
There is no civilian incident to date that could not be easily handled with civilian only weapons. Police should have Ruger Mini 14 rifles and 12 gauge pump shotguns. Most importantly they have radios that can call in virtually limitless numbers of more cops. AR15's are military weapons in civilian legal form. The police are NOT the military. Dress like a soldier, act like a soldier. Train like a Soldier, fight like a soldier. Cops are NOT soldiers.
Our country got along just fine for 200 years without SWAT teams. They are a menace to our free society and need to be gone. Ninety nine percent of the time SWAT teams are used as show of force. They show up after an event has taken place to show off their MILITARY full auto weapons, Battle Dress Uniforms and other military toys. There is no incident that cannot be handled by normal peace officers who dress and act as cops.