The Alliance has compiled this set of terrorism resources from throughout the nonprofit and museum sector.
The Centers for Disease Control and Prevention has guidelines for emergency preparedness, including biological and chemical agents, radiation, and water safety. It also has contact information for county and city health departments.
The Nebraska Emergency Management Agency has a helpful list of things to do to plan before and after an act of terrorism occurs.
The American Red Cross has a fact sheet titled Terrorism: Preparing for the Unexpected. It suggests items for a disaster supply kit, offers a first-aid primer and gives tips on sheltering in place.