The main reason why this building can't be cleared of zombies is a lagging. Because at the one time you are immediately attacked by a large horde of zombies. Which simultaneously rises through the script. And immediately comes at you, from all sides. This causes lags, during which the fastest of them can reach you and deal critical damage. And if even you can get back to the first room, you can't shoot them all with shotgun or pistol. You can be saved only if you have assault rifle, submachinegun or autoshotgun. And this is not the main problem what they can hit you when you're lagging or press you by count. The main reason is a crashing because of lag. So sad, this must to be fixed. Or not, this is just my opinion...
