California shooting: Ian David Long identified as gunman who killed 12

The shooter who opened fire inside a California country bar Wednesday night has been identified as 28-year-old U.S. Marine veteran Ian David Long by police.

The Borderline Bar & Grill in Southern California shooting left 13 dead, including the shooter. Police said they cannot confirm a motive for the shooting.

WATCH: 12 killed in mass shooting at California bar; gunman also dead

2:08 12 killed in mass shooting at California bar; gunman also dead

At a news conference Thursday morning, Ventura Country Sheriff Geoff Dean said Long was found dead. Police believe he shot himself, but are not yet sure of the details that led to his death.

At least another 10 people have been injured.

WATCH: Police identify California bar shooter as Ian David Long

3:04 Police identify California bar shooter as Ian David Long, say deputies called to his house last April

Several people from inside the bar told media that the shooter was wearing all black. His face was partly covered as he shot at people in the club.

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Police said the 28-year-old used a .45-caliber Glock handgun, which was purchased legally.

READ MORE: Ron Helus, veteran sheriff’s sergeant, ’died a hero’ in California mass shooting

Long’s gun had an extended magazine on it, Dean said, which enabled it to hold more rounds and fire more shots before reloading. Dean said it’s not clear if Long did reload during the shooting, or how many times.

Dean said Long had previous run-ins with police, including one instance in April where he acted “a little irrationally.” However, at the time, the police force’s mental health crisis team determined Long didn’t need to be taken into custody.

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He had other interactions with law enforcement, including a traffic accident and an incident when he was the victim of a battery at a bar.

WATCH: Eyewitness saw shooter’s face, heard ‘lots of gunshots’

2:03 Eyewitness saw shooter’s face, heard ‘lots of gunshots’

CNN reported that according to Department of Defense records, Long served on the Marine Corps from August 2008 to March 2013.

READ MORE: 13 dead, including police officer, after shooting in California country bar

Law enforcement officials were seen outside of Long’s Thousand Oaks bar, Calif. home Wednesday morning. The sheriff said they have filed a search warrant for the residence.

— With files from The Associates Press