THOUSAND OAKS, Calif. (AP) - The Latest on the mass shooting last month at a California bar (all times local):

10:55 a.m.

Authorities say a sheriff's deputy killed in a mass shooting at a Southern California bar was shot five times by a gunman who killed 11 others, but struck fatally by a bullet fired by a highway patrolman.

Ventura County Sheriff Bill Ayub says Sgt. Ron Helus died from a bullet wound that struck vital organs shot by a California Highway Patrolman who joined him in the gun battle Nov. 7 at the Borderline Bar & Grill in Thousand Oaks.

Helus was among 12 people killed at the bar during the shootout. Gunman Ian David Long took his own life.

Authorities don't know what drove Long to kill.

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10 a.m.

Authorities planned Friday to announce what they call a "significant development" in their investigation of last month's shooting that killed 12 people at a popular Southern California country music bar.

The development was to be announced at a news conference at the Ventura County Sheriff's Station in Thousand Oaks, Detective Eric Buschow told The Associated Press. He declined to elaborate.

Investigators have previously said they don't know why 28-year-old Ian David Long stormed into the Borderliine Bar & Grill in Thousand Oaks on Nov. 7 as people were dancing to country music.

He sprayed the bar with gunfire, killing 12 people before taking his own life.

Among those killed was sheriff's Sgt. Ron Helus, who was ambushed as he rushed into the bar to confront the gunman.

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