Several times I have been successfully attacked by zombies who are no where near me. the first 2 I had locked in a room and they were able to hit me while I was outside the house - no matter how far I run they continue bashing me.
The last occurrence the zombie was stuck outside the fence while I ran into the house. I witnessed this zombie attacking the air from outside, and as he did I was taking the damage from the second floor.
Ran into 2 others whom could not be killed with fireaxe or bullets.