If you enter private property forcibly, you should expect to be shot at. If you shoot back while having forcibly gained illegal entry to private property, you've committed a crime. It seems fairly open and shut to me. The only hold up is police and court system corruption along with a healthy dose of good old fashioned racism. Again, just my opinion.
For someone outside the US this is such a crazy statement.
America has more than just a few home invasions and murders. If someone is trying to break into your home, especially at night, there's a high chance that that person is not only willing to maim or kill you, but planning to do so. America has around 1 million home invasions per year and help isn't always nearby. Waiting can easily result in the victim being killed.
The man who shot at police here was worried that someone would end up killing him or his girlfriend. Unfortunately, he was right.