The grim revelation, made public exactly a month after the Nov. 7 massacre at the Borderline Bar and Grill, adds yet another tragic element to what witnesses and authorities alike have described as a chaotic, terrifying scene at the country-music venue.
When the gunfire ended, a dozen people had been fatally wounded - including Ventura County Sheriff's Sgt. Ron Helus, 54 - and the gunman killed himself with a single shot to his head. Police have identified the attacker as 28-year-old Ian David Long, who has a history of angry behavior, and said they are still investigating what could have motivated the rampage.
Helus responded to reports of the shooting by heading with a California Highway Patrol officer into "what can only be described as a combat situation," Ventura County Sheriff Bill Ayub said during a somber briefing Friday. Ayub said after Long shot bar patrons and employees, he waited for law enforcement to respond and then "almost immediately" began shooting at them.
"Sgt. Helus was struck five times by gunfire from the suspect," Ayub said. "Today, I'm deeply saddened to inform you that Sgt. Helus was also struck by a sixth bullet, which we now know ... was fired from the CHP officer's rifle."
That sixth bullet was fatal, Ayub said. The gunman's bullets hit Helus and "caused serious injuries but potentially survivable injuries," Christopher Young, the Ventura County chief medical examiner, said at the same news briefing. But the highway patrol officer's bullet hit Helus's chest and his heart, Young said.
"This is sad news and a tragedy, but ultimately, this was the most severe injury sustained," Young said.
The highway patrol officer was not identified; the agency described him as a nine-year veteran of that force who is currently not on duty.
"He's devastated," said L.D. Maples, chief of the highway patrol's coastal division.
The explanation for Helus's death speaks to the frenzied, dangerous and often unclear situations faced by law enforcement officials who head to active shooting scenes. Officers responding to such attacks across the country have later described the sheer terror and confusion they encountered, in some cases not knowing how many attackers were opening fire or entering rooms without knowing if a shooter was poised behind the door ready to fire.
That confusion can also lead to fatal mistakes for law enforcement officers trying to help. Prince George's County police detective Jacai Colson was responding to an attack on a police station in 2016 when another officer, mistaking Colson for a threat, shot and killed him.
In Thousand Oaks, Ayub said Helus "was clearly not the intended target" of the shot that killed him. While Ayub said specific facets of that shot were still being investigated, he noted that the scene inside the bar was dark, smoke-filled and unfolding rapidly.
"This is a tragic detail that I don't think was avoidable," he said.
Police have said Long fired more than 50 rounds from a Glock .45-caliber pistol during his attack inside Borderline. He lobbed smoke grenades that fueled the confusion inside, authorities say, sending people fleeing the carnage leaping through windows or scrambling for shelter in the bar's attic. Young, the medical examiner, has said he has no evidence suggesting any other victims were struck or killed by the responding officers.
The sheriff said blame for Helus' death - as well as the other deaths and injuries that resulted from the massacre - rested solely with the attacker, who Ayub did not name during his news briefing.
"He alone created the violence and he alone bears the responsibility for his course of action," Ayub said. "He went there with a plan and a purpose and that was to take innocent lives. The burden lies solely with him, not those who tried to save lives, those who tried to escape and certainly not with those who died while simply trying to enjoy an evening with friends."
This article was written by Mark Berman, a reporter for The Washington Post.