I know heroes do not block line of sight but do zombies? (Can you Fire at a zombie in a space in range if one is blocking the line of sight)
And if that wasn't the case, just blast right through em! But no... what mqstout said.
I would have to say as long as they are in LOS then it all fly's.
Hero's have great aim... except when I control them, so they can shoot around any person/zombie.