. Description: there is an area bounded by walls that contains zombies. The govt authorities find out signs of human in the area . They send a team to find out who the people really are. The team comes to know that zombies have evolved and found a way to survive.

Sounds a bit like Doomsday... except there were only normal human survivors behind the wall, not zombies. Something about the zombie angle does sound familiar, though.

Thank you very much :)