Iron Golems Not Attacking in Minecraft?

I have a very large npc village in minecraft. I did not make the village either. There's 3 iron golems that spawned because of the size of the village and amount of villagers. They do attack during zombie raids sometimes, but not always. In one small section of the village where most of the villagers go, they do absolutely nothing during a zombie raid and causes deaths of all the villagers in the area, if the zombie goes out of the small area, then they killed. I tried spawning golems in that particular area but they still do nothing, they even walk into the crowd of zombies and still do nothing. Why is this? Why do iron golems ignore everything in that one area? It is also the xbox 360 version.