The officers has a warrant, and a legal right to enter the apartment, but they're still lucky to be alive especially the one who got shot near an artery. Even if you bang once or twice on the door the average person won't wake up and be fully conscious for at last 15-30 seconds after a loud noise. If their instinct tells them someone's home invading, then they're going to pull out their weapon in a state of disorientation and people are probably going to get shot. This is why the SWAT commander