The National Fire Protection Association (NFPA) report has tracked on-duty firefighter deaths in the United States since 1977.
[1] Of 2019 on-duty firefighter deaths in the U.S., 54% were due to medical emergencies, overexertion, or stress (included in this category were 22 heart attacks or other sudden cardiac deaths, 2 strokes, 1 heatstroke, and 1 suicide); 13% by fire progress (such as being trapped or overrun) or explosions, 8% were struck by a vehicle, 8% died in vehicle crashes, 6% fell from heights (such as buildings, fire apparatus, roofs, and bridges), and 10% died from other causes.
[1] An analysis of FBI data published in 2019 in the Criminology & Public Policy found that police line-of-duty deaths in the United States fell 75% between 1970 and 2016.
"[7] A 2018 white paper, commissioned by the Ruderman Family Foundation, found that U.S. police officers and U.S. firefighters were more likely to die by suicide than in the line of duty.
[9] A comparison of police deaths in New York City and Greater London from 1900 through 1999 found that "both intentional and unintentional occupational police mortality rates were significantly greater in New York compared to London"; the study officers identified "socioeconomic, cultural, and occupational factors" (including the widespread prevalence of firearms in the U.S.) as the likely factors explaining the discrepancy.