Getting killed through walls

A few times in Redsec, i've been killed through walls, and I don't understand how that's possible. For example, I was on the second floor of a house looking outside and someone was outside running to the house, we exchanged fire, and I moved to the opposite side of the house to a small balcony to equip armor. I'm not sure if they even entered the house, but they either...
* shot me through the house completely penetrating several walls or
* entered the house and from the ground floor shot me through the L2 floor.

How is that possible? I can't kill people through walls. I've seen people killed through the garage door, but that's it.