Good, bad, I'm the guy with the gun..

Well, you have a weapon, so if it tries anything, you shoot it. Simple. So, you walk out of your apartment, contemplating on locking your door, just in case you need to get back up there, and quick, you don't lock it. You proceed down the steps, when the strange being drops your friend, and runs after you. Without hesitation, you shoot it in the leg. It trips, but gets right back up. You think, "What in the?" So you shoot it again, this time in the head. It drops to the ground and doesn't get back up. By the time you figure out that it's actually dead, your buddy jumps up, and comes after you. Here you make an important decision. You...