VENTURA, Calif. – Six bullets struck a California officer who responded to the Borderline Bar & Grill in Thousand Oaks last month. One came from a California Highway Patrol officer's rifle, the sheriff said.

At a news conference Friday on the Thousand Oaks shooting, Sheriff Bill Ayub announced it was the shot by friendly fire that was fatal for Ventura County Sheriff's Sgt. Ron Helus.

The other five shots came from Ian David Long, 27, of Newbury Park. Long walked into the country bar on Nov. 7, and opened fire on bar patrons, killing 12 people before turning the gun on himself.

Ayub put the responsibility for the deaths, including Helus', on Long.

"Today, I'm deeply saddened to inform you that Sgt. Helus was also struck by a sixth bullet, which we now know, through forensic analysis by the FBI's crime laboratory was fired from the CHP officer's rifle," Ayub said. "Tragically, it struck vital organ and was fatal.

"This was a dynamic, chaotic event that led to a very brief, but furious gun battle between the killer and the lawmen," he said.

In a statement Friday, California Highway Patrol Commissioner Warren Stanley extended his condolences to Helus' family, friends and colleagues.

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"The California Highway Patrol (CHP) is profoundly saddened to learn of new details emerging from the horrific incident which resulted from the deadly actions of suspect Ian David Long at the Borderline Bar on Nov. 7. ... The suspect, who had been lying in wait for the officers to arrive, immediately ambushed the pair with gunfire as they entered the building. While the officers' actions prevented the suspect from shooting more patrons, tragically, during the brief and chaotic gunfight that ensued, a round by our officer struck Sgt. Helus."

The statement concluded, "Without question Sgt. Helus died a hero while protecting his community from a dangerous criminal. In the face of danger, Sgt. Helus courageously upheld the oath he took to lay down his life rather than swerve from the path of duty."

The CHP officer was described as a nine-year veteran with military experience. He was told Wednesday about the fatal hit to Helus' heart and is on personal leave, officials said.

At a Nov. 27 news conference, Ayub and FBI officials said a motive had yet to be determined although there was no evidence that the suspect in the shooting, had been radicalized.

Using a legally purchased gun equipped with an illegal extended magazine, Long fired more than 50 rounds into the crowd and threw smoke bombs.

Nov. 15:Fallen California Sgt. Ron Helus remembered for bravery, service, faith

Law enforcement officers, including Helus, responded to the scene within minutes and entered the bar where they were immediately met by gunfire. Helus was fatally struck multiple times.

Long struck 13 people with gunfire, only one of whom would survive.

In the days that followed the shooting, FBI investigators worked alongside sheriff's homicide detectives to collect hundreds of pieces of evidence from Borderline and Long's home. An estimated 90 FBI investigators were on scene for eight days to survey the crime scene and Long's home, Ayub said on Nov. 27.

Digital media from Long also was found, which will be investigated by the FBI, Delacourt added. He said a shooting reconstruction was being created although it would not be completed for some time.

Follow Christian Martinez on Twitter: @ChristianM_CA