Late Thursday night, a man opened fire on the Borderline Bar & Grill in Thousand Oaks, CA, during a college event. He killed 12 people, including Sgt. Ron Helus, who rushed to the building when he heard the man still shooting inside the bar.

Reports have surfaced that authorities identified the shooter as former Marine Ian David Long, 29, and that neighbors said “he went by his middle name.”

The Gunman

From 6ABC:

Shortly before 7 a.m., deputies swarmed a neighborhood in the Newbury Park area, focusing on a particular home, which they roped off with crime tape.

Investigators were knocking on doors of surrounding residents to find out what they may know about Long.

One neighbor who knew Long said he was a veteran who suffered from PTSD. She said, “I don’t know what he was doing with a gun.” Others said Long lived at the home with his mother.

His gun, which appears to be a .45-caliber handgun, was purchased legally, according to ABC News. AP reports that he also deployed a smoke device.

Police found him with a self-inflicted gunshot to the head.

Ventura County Sheriff Geoff Dean explained to the press that they’ve had run-ins with Long:

Sheriff Geoff Dean, who is set to retire on Friday, said Long may have suffered from post-traumatic stress disorder and was known to law enforcement officials due to several unspecified “contacts” stretching back multiple years. Long served in the Marine Corps from August 2008 to March 2013, with a deployment in Afghanistan between November 2010 and June 2011, military records show.

“We’ve had several contacts with Mr. Long over the years, minor events such as a traffic collision. He was a victim of a battery in a bar in 2015,” Dean said, adding that the bar in 2015 was a different establishment than Borderline.

Dean said the last interaction between Long and authorities occurred in April, when police officers were called to Long’s house in Newbury Park, about five miles from Borderline, after reports of a disturbance. When they arrived, officers found Long “irate and acting irrationally,” leading to a crisis intervention team being summoned. The team, however, cleared Long and said they didn’t feel he was qualified to be taken into custody.

“Obviously, he had something going on in his head that would cause him to do something like this. Obviously, he had some sort of issue,” Dean said of Long.

The Shooting

Witnesses said that at 11:20PM local time, the man dressed in black threw smoke grenades into the bar and opened fire as confused and scared patrons struggled to find a way out.

Officers arrived on the scene and heard the man shooting inside the bar.

Helus arrived first on the scene and did not hesitate to try to enter the bar in order to stop the gunman. The gunman hit Helus as soon as he walked into the building.

Helus spent 29 years on the force and was one year away from retirement. He leaves behind a wife, who he called right before he went inside, and a son.

“Ron was a hardworking, dedicated sheriff’s sergeant, he was totally committed. He gave his all. And tonight, as I told his wife, he died a hero because he went, he went in to save lives, to save other people’s lives,” declared Ventura County Sheriff Geoff Dean.

The gunman killed 11 other people inside the bar and authorities found him dead as well.

The popular bar for college students hosts a college country night every Thursday. This week had students from Pepperdine University, California Lutheran University, and California State University Channel Islands.