If you approach a house and receive gunfire from the house you have many tasks to perform, some very fast. You have to return fire and seek cover; those are the first two tasks. Next you must communicate, first to any other officers at the scene and second to your dispatch and any officers on the way to the location. You may have to withdraw a significant distance, you may even have to return to your car and drive away; a rifle can hit targets hundreds of yards away. Reload as soon as possible, from behind cover if you can. You may have to rescue a downed officer. If that’s the case, don’t rush in and get yourself shot too. Wait for other officers to provide covering fire, use a patrol vehicle or better yet an armored vehicle for cover to get the injured officer.
Direct responding units to set up a perimeter. Make sure that responding units don’t drive in front of the location on the way to their perimeter location. Hand off the coordination to a supervisor as soon as possible. It’s hard to coordinate responding units and return fire at the same time. Once a close perimeter is set up, a far perimeter needs to be set up. A close perimeter keeps the suspect inside the location; a far perimeter keeps other people from entering. It is important to keep traffic from entering the kill zone.
A command center needs to operate fairly close to the location, but outside the observation of the suspects. It has to have a large open space, and good access to and from the location. You need space for fire department, paramedics, Red Cross, news media and a large number of police vehicles. Don’t try and do too much by yourself; don’t rush in unless it gives you a tactical advantage. Deploy SWAT teams and negotiators to deal with the situation; that’s what the SGT Says.