Once again, the shooting ended when a good guy with a gun killed the bad guy with a gun.

An off-duty FBI agent may have averted a mass-shooting Saturday night when a gunman walked into a sports bar packed with patrons attending a high school reunion and shot his ex-wife and her new boyfriend.

The gunman was killed when the agent, whom police would only officially identify as an off-duty law enforcement officer and subsequently asked not to be named, shot the suspect after gunfire erupted about 8 p.m. at the Fifth Quarter Sports Bar and Pizzaria.

The suspect and the two targets of his initial burst of gunfire ultimately died — the suspect at the scene and the other man and woman at a Peoria hospital.

This seems to have been a domestic violence homicide that played out in a public place. Authorities feel that the agent who dropped the murderer may have averted a mass shooting.

“It’s very difficult to say. You can play the ‘what if’ game over and over again, but I think it’s pretty clear in his case the presence of this officer and his ability to take very quick and very decisive action prevented a further tragedy,” East Peoria Police Chief Ganschow said.

Ganschow said more than 100 witnesses provided contact information to police, including members of the East Peoria High School class of 1999, though many patrons were not part of that party.

There were numerous patrons between the shooter and the exit, and authorities seem to think that the murderer would have fired upon anyone who got in his way. Everyone in attendance is very lucky that this agent was there, was well-trained, and was armed.