VENTURA COUNTY, Calif. – It has been determined that the fatal round claiming the life of a Ventura County sergeant during a mass shooting came from friendly fire.

The bullet responsible for killing Sgt. Ron Helus during November’s mass shooting at the Borderline Bar & Grill was fired by a California Highway Patrol officer, authorities said Friday.

Helus—who was nearing retirement—was also struck by five rounds from 28-year-old gunman Ian David Long, reported Fox News.

friendly fire

Friday it was announced that Sgt. Ron Helus was killed by friendly fire after also being shot five times by a gunman who opened fire inside Borderline Bar & Grill Nov. 7. (Ventura County Sheriff’s Office)

Yet is was dreadfully the sixth round, fired by a fellow law enforcement officer, that struck Helus in the heart and killed him, Ventura County Sheriff William Ayub said during a Friday press conference.

“It was just a tragic detail that unfolded so rapidly, in my view it was unavoidable,” Ayub said. “They were ambushed almost immediately.”

And now beyond the death of a heroic cop, is another fellow peace officer who will suffer the burden of this horrific event.

Helus responded to the scene after Long stormed into the Thousand Oaks bar Nov. 7 and sprayed the crowd with gunfire, killing 12 people.

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Long threw smoke grenades into the crowd, obstructing what they could see before he opened fire. Furthermore, he then used a flashlight with a laser sight attached to his .45-caliber semi-automatic pistol as he fired at the establishment, which was filled mostly with young people dancing to country music.

Helus has been credited as being a hero after he rushed into the bar to confront the gunman.

Ron Helus

(Graphics courtesy Rose Borisow GrafX)

Panicked patrons smashed windows, dived under tables and piled on top of each other in an effort to dodge the gunfire.

Long, the homicidal gunman, later killed himself.

Thousand Oaks gunman

Ian David Long shot and killed 12 people at a country music bar last month. (California DMV)

Ayub emphasized the fatal shot did not diminish the heroism shown by the officers. The 9-year CHP veteran was not identified, but remains on leave.