Black ops Glitch messed up?

Ok. So i was playing dom on grid and i ran up to the stairs(where the balcony is) and i got shot and killed by this guy with a famas. I was wondering how i got killed since i was behind a wall. I looked at the killcam and i saw him shooting at a guy who was OUTSIDE jumping off the balcony(supposedly me) ,when i was on the stairs. WHAT HAPPENED???