"The National Violent Death Reporting System (NVDRS) provides states and communities with a clearer understanding of violent deaths to guide local decisions about efforts to prevent violence and track progress over time."
Data is collected on homicides, suicides, death where individuals are killed by law enforcement in the line of duty (legal intervention), unintentional firearm deaths, and terrorism related deaths. Currently, 40 states, the District of Columbia, and Puerto Rico participate.
NVDRS data describes the "who, when, where, and how" of violent deaths which can lead to a better understanding of the "why". You can use NVDRS data to guide your prevention programs, policies, and practices - CDC