The gunman who murdered 12 people at a California bar Wednesday night has been identified as Ian David Long.
Long, 28, was a former Marine from served from 2008-2013.
At approximately 11:20 PM local time, Long, dressed completely in black, entered the Borderline Bar & Grill in Thousand Oaks, California, where many college students were celebrating, and opened fire with a Glock 21 .45-caliber handgun. He shot an unarmed security guard before opening fire on the bar's employees and guests.
Police quickly rushed to the scene and engaged in a shootout with Long.
Sheriff's Sgt. Ron Helus was the first to arrive on the scene and engage with Long. Helus was shot several times and was pronounced dead at the hospital.
Long's body was later found near the bar's entrance. It is believed that he shot himself.
The motive for the shooting remains unknown, according to Sheriff Geoff Dean.
Sheriff Dean said that Long was "known" to police following a number of incidents over the last five years.
“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.
Dean said that Long may have suffered from PTSD following his service in Afghanistan in 2010 and 2011. "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."
He also said that there was no evidence Long had targeted the bar employees or any victim in particular.
Several survivors of the 2017 Las Vegas massacre were present at the bar during the shooting Wednesday night.