The military's way of maintaining security during the lockdown...

So I guess the military thought that it would be best to lock all the citizens into one space, that way they could keep all the citizens accounted for. I guess that kinda makes sense. But if the military planned on stuffing all the citizens into one space, couldn't they at least keep it safe from the infected from entering. I mean, the infected dad just straight up pushed open a door and then started biting everyone. One infected infiltrator, pretty much ruined the entire lock down plan, and made the situation even worse. At least if the people weren't stuffed into one metal room, they could've had a chance of escaping. I think it would've been easier to just tell everyone to stay in their apartments, and let the military heavily secure the location, as they sniper oncoming infected from the roof tops. Stuffing everyone into a metal box was just overkill.