When you get to the part when the rabbit says "Oh crap, he's after my key" and you must get to the tower with all the SWAT members, run straight through that part and into the tower. Go up until you can hide behind a wall and aim up to where their heads will appear when they come towards you. Wait and kill them, then go up the steps and you will reach a certain point to where the rabbit will be just above your head with a SWAT team member guarding him. Lean towards the left side of the wall and go up slowly. Go up just enough so that you can see the rabbit's head. It will require about five or six head shots to kill him. Shoot it in the head twice with a shotgun, or any other gun you desire. The SWAT guard will be alerted. Run down the steps a short distance and do the same thing as before -- wait for his head to appear and shoot. Repeat the process of going up and revealing just the rabbit's head and shoot. After he is dead, get the key and go out of the tower balcony. Do not get the sniper -- it is too risky and uses up the ammo that you earned. Run around at least two times then go back in the tower. Wait behind the top of the steps for the men. Aim down in the center so that when they walk up, you can easily kill them with one head shot. There are at least ten men. Then, leave the tower and go towards the gate.