hide under something. He runs off. Peek out a little bit (until you are no longer in first person) then aim your gun in his location. He will creep out. Shoot him with the mosin nagant (if you have it. It does a heck of a lot of damage to his stamina). Quickly hide back under and he will eventually run off again. You never have to get hurt. The second time around... There is only ONE hiding spot, and it's a little tricky. There's like no way you can beat him without hiding. If he gets close, goodbye. Anyway, the second time you fight him, you have to go all the way back to the beginning of the stage and hide under your transport truck. You have to peek out quite a bit to see him because he is up a ramp in the front of your truck (and you can only crawl under the SIDE of it. I finished him off with a seeing view of only a crack. Ah... good times. I hope this helps.