Sounds like an ambush. Unfortunately when responding to a domestic call, you are always concentrated on getting to a particular adress and not so much concerned about a bad guy waiting your arrival. Tactics need to change. The cops come first, then the mess gets cleaned up.
It’s a problem. When they’ve done what you suggested, perfectly innocent but confused people have ended up getting shot, and then the cop ends up in the midst of major trouble - or, conversely, the police don’t go in until it’s too late to save the victim.
These are horrible calls, and every cop hates getting them, because it’s a no win situation. Even if the guy blows his own brains out, the cops get blamed - and a lot of times he decides he wants to take out a few other people with him. Also, the wife or the whatever (the “victim”) will often then turn on the cops and attack them.
Shot from behind a bedroom door.
http://www.dailymail.co.uk/news/article-5224723/Multiple-deputies-shots-fired-Denver.html