Yea, just tried it alone - there seems to be no place to get cover so I ran around, then they got me from both sides.
EDIT: I just found out it's much easier if you weld a door behind you - they will go around this obstacle and attack you from the front. ...Seems to be pretty easy then ... until they suddenly overrun you xD
Well, but there's one thing missing: a door at the shop on the lowest floor.