Then look out into the street and start setting off explosive barrels to kill some of the headcrabs and zombies in the street. Step out onto the ledge and kill the black headcrab if Grigori missed it. You can start to use your guns for this period of time. Shoot the zombie in the room with your pistol while you wait. Give Grigori a second or two to kill a few of the other things along the ledge. Be careful though, since there is one zombie waiting in the room with you. Father Grigori is clearing off the ledge.
Go up the stairs and race toward the gunfire. Punt it with the gravity gun or just shoot it. Climb in and go down the hallway and wait for the next area to load. Walk along the little catwalk until you get to a window. You’ll see Grigori again and earn a bit of praise. Jump onto the catwalk when it gets to the top. Crouching should help you stay on top of the moving car. You need to pull the next lever and jump onto the car to avoid the horde of zombies behind it. Pick off the rest with your gravity gun or even your submachine gun, since your ammo is probably maxed out anyway. Pull the lever when they step into the existing blood pool. Use it to crush as many of the five or six coming toward you as you can. Break the boards off of the exit and head into the street. Thin them out with a few oxygen tanks before you drop down. There are four headcrabs and a zombie on the ground below. Drop down to a plank bridge and go into the window at the end.
