Following an act of terrorism, mass violence, or other tragedies, a range of local, state, and federal organizations and agencies mobilize to support affected individuals and communities. Some respond immediately, while others become involved later, offering resources and services as needs emerge.

As recovery continues, many organizations provide intermediate and long-term support, addressing emotional, psychological, and practical challenges. Federal agencies also play a key role, particularly when an event overwhelms local capacity. They administer specialized programs, operate under defined jurisdictions, and support national recovery efforts through their expertise.