Need Help on Dead Space 2!?

Okay, there are no glitches here. Im at the part where your with Stross and Ellie, where the train gets stuck and you have to get out and find the problem, only be be completely ambushed by necromorphs. I only have one necromorph to go, (the one stuck to the wall, who shoots out the babies with one tentacle) but i have NO ammo, i used all the body parts on other necromorphs, AND only one more hit and i'm dead. Unfortunately i can't go back to my last save because I saved in the middle of this situation. I tried just running to the door, and dodging it, but it just swipes me and kills me with one hit. HELP ME. What can I do? I've been stuck here for a while.