I wonder if the tip was that Cupcake was seen at the complex, but perhaps she's no longer there? It seems to me that if the police believed Cupcake was being held in an apartment there, they wouldn't allow people to mill around, or even go back to the their own apartments. If they're expecting to have to kick in a door and charge in armed, that would put residents in other apartments at risk.
I'm not feeling like this is a rescue mission (I hope I'm wrong). Perhaps it's an evidence/information gathering event. My mind isn't quite ready to go to a darker place.