of course you have the complication of a couple of officers who remain in that building and the shooter has the advantage. they know the exactly the layout, where to hide. and so the police were dealing with much more complicated situation than you usually have. this began with narcotics officers going to that building. this is an area just north of center city philadelphia. and so at this point, now, i think they're going to wait a while to see if they can hear any other sign of life from inside that building and figure out how to get in there to try to extricate those officers, protect the people who are in the building and get the shooter or shooters who are still there. >> some of those officers, i think they're bike officers that were involved in the narcotics raid initially or the serving of a warrant. thank you. >> joining us is the former philadelphia police commissioner and special agent, both cnn law enforcement analysts.