The Las Vegas Metro police conducted training for active shooter response. Two men dressed and equipped like some recent active shooters have been, attacked city hall with simulated ammunition. Officers responded to stop the threat.
If the bad guys have body armor, and rifles the good guys need access to the same if the community wants proper protection. It is not militarized police, it is police meeting the challenge created by the criminals. Remember US police rarely walk around on patrol with a rifle, these tools only come out when specific events happen.