asking literally thousands of people to barricade themselves in a room. they're all going to be calling the main switchboard of the police department. and now the police have this really horrible job of going through this massive facility that you're showing right now, floor by floor and room by room. >> here's what they're telling me on the associated press that the gunman is holed unon the eighth floor at this building at johns hopkins hospital. that they have now set up a tactical situation and operation to try and go in and gain control of the situation. it looks like parts of the hospital are being evacuated but not the entire complex, which would make sense because some of these buildings are not connected to that main hospital building. and have more than 30,000 employees they're saying. more than 1,000 beds. so they are trying to isolate the parts of the hospital that could be, i presume, in most immediate threat. >> well, in a situation like this, law enforcement's doing