I bet it is close to 0.

In recent years, the total number of fire deaths is 3000 to 4000 per year:

https://www.usfa.fema.gov/data/statistics/fire_death_rates.h...

Many of those deaths will have happened regardless of the response.

In some sense, across 300 million people, even 3000 is close enough to zero (there's more than 2.5 million total deaths each year in the US). That doesn't mean that improving fire response isn't important, but it might not be a very good place to look for incremental improvements in mortality.