I was in the Balota airfield in the tower to the right of the main gate if looking from inside the airfield.
I was trying to shoot at a zombie to the south of me while crouched, but being crouched I couldn't shoot over the side of the tower, so I went to stand up to shoot and died instantly. Then my body fell through the bottom of the tower. I had a zombie aggro'd on me at the bottom of the tower when this happened, but he wasn't hitting me.
My friend was watching me when this happened and confirmed everything I thought, I didn't get shot, I just instantly died for no apparent reason.
My gun was an SKS, dyed black, with a PU sight, and an SKS bayonet. Although I doubt that's relevant to the issue.