Here's an attempt at an answer:
"Dispatch gets the 911 call saying shots have been heard or fired, and the closest police units respond. Park Police gets a call as well and they show up too," [Homeland Security and Emergency Management Agency Director Chris] Geldhart says. Those earliest responders, no matter their rank, are responsible for setting up an "Incident Command System," which the Department of Homeland Security describes as an "incident management approach" that:
Every law enforcement agency in D.C. knows how to set up an ICS, according to Geldhart. As representatives from more agencies begin to show up, the responders rely on interoperable radio systems to keep everyone on the same page. These radios allow users to talk across agencies, though Geldhart did say that Navy Yard police were not able to communicate via radio with people outside the building (Congress is looking into this claim, as well as a report that Capitol Police were told to stand down). Interviews and intelligence gathered by various agents, largely from witness and survivor interviews, is relayed to the ICS through the radios, and then vetted.
- Allows for the integration of facilities, equipment, personnel, procedures and communications operating within a common organizational structure.
- Enables a coordinated response among various jurisdictions and functional agencies, both public and private.
- Establishes common processes for planning and managing resources.
