My partner was kneeling in the tower of the Firehouse at the NW Airfield trying to pick up an item. I came up the stairs, and as I reached the top I somehow knocked my friend out of the windows where he landed on the roof and died. He was in the kneeling position and remained in the kneeling position as I watched him get lifted into the air and pushed out the window where he fell. I seemed to have a "force field" or something as I came up the stairs. I don't know if this is a collision problem, or an issue with the windows, or if I even can push someone out a window.