Had initially respawned, and was carelessly running around looking for loot, and I came across a couple of zombies. I initially noticed a military and vanilla zombie as I was in a house, I attempted to trap them in the house, but I think I only succeeded in trapping the vanilla zombie. I then ran to a nearby appartment, closed the doors, I think just in time to keep the military zombie out. I could not see said zombie inside, but the military zombie was able to attack me. I went into another room, and saw the zombie doing the attack animation outside, and this corresponded to me getting damaged. Realizing there was a glitch, I attempted to run upstairs up two flights of stairs to avoid the zombie, to no avail. I ran down one flight of stairs, and saw two zombies both appearing to attack the wall, but their attacks were hitting me.