National Incident Management System Basic Guidance for Public Information Officers (December 2020) [open pdf - 762KB]
From the Introduction: "FEMA developed this guidance in coordination with Federal, state, local, tribal, territorial, private sector, and nonprofit Public Information Officers (PIO). This publication provides operational practices to help PIOs perform their duties within the National Incident Management System (NIMS) Command and Coordination structures. Before, during, and after an incident, coordinated and timely communication to the public is critical. Effective communication can save lives and property, and can promote credibility and public trust. PIOs are key members of Incident Command System (ICS) and Emergency Operations Center (EOC) organizations, and they work closely with officials who are part of Multiagency Coordination Groups (MAC Groups). PIOs advise the Incident Commander (IC), Unified Command, and EOC director on public information relating to incident management."
Federal Emergency Management Agency: https://www.fema.gov/