When the crowd realized that they could not enter, they immediately became frustrated. This was especially so for those that had their children inside of the territory.
This was to be expected. Previously, when their children were being taken away, they had no choice considering that outside was completely dangerous. So, they thought that being inside this territory was actually the safest thing that they could do.
But now, it was completely different. After all, they so far, had not encountered any danger other than the other groups that had formed their own bases. Of course, there was always a group of people that wanted to rob, catch others to work for them and so on.
Since there were no zombies in the city, the parents thought that they could finally have their children. After all, there was no need for them to continue being separated from their children, if the reason did not exist anymore.