The Crime Prevention Research Center reveals the FBI has underreported how frequently armed citizens stop active shooters.

The agency (FBI) reported that armed citizens stopped only 11 of 252 active shooter incidents, or about 4.4 percent.

“We discovered a total of 360 active shooter incidents from 2014 to 2021, and found that an armed citizen stopped 124 of these” (or 34.4%)

even those numbers could be low, since much of the media trends toward the anti-gun side of the equation and might not report all such incidents.

https://www.firearmsnews.com/editorial/fbi-underreport-defense-gun-congress-testimony/467858