This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

A gunman opened fire in a packed bar in Thousand Oaks on Wednesday night, killing at least 12 people, including a sheriff’s sergeant, and wounding others before he was found dead at the scene, according to Ventura County Sheriff Geoff Dean.

The suspect has been identified as Ian David Long, a 28-year-old former U.S. Marine who resided in Newbury Park, Dean said.

Related: Massive Hill Fire breaks out a few miles from Thousand Oaks shooting site

Authorities said Long was armed with a Glock 21 .45-caliber handgun when he stormed into the Borderline Bar & Grill – located at 99 Rolling Oaks Drive – and began firing at security, employees and then the large crowd inside, sending hundreds of panicked people fleeing.

Law enforcement personnel were dispatched around 11:20 p.m. after receiving multiple 911 calls regarding shots fired at the bar.

A sheriff’s sergeant and two California Highway Patrol officers were the first to arrive on scene, responding within minutes, Dean said. After hearing gunshots, they went into the restaurant.

Sgt. Ron Helus entered and was struck by multiple bullets, the sheriff said. The CHP officer went out and secured the perimeter until additional units arrived, then went to rescue Helus from the line of fire.

Additional units from multiple law enforcement agencies responded and made entry.  They found 11 victims killed inside.

The sergeant died at a hospital sometime before 2 a.m. Helus, a 29-year veteran, was looking to retire next year. He lived in Moorpark and is survived by his wife and son.

“Ron was a hard-working, dedicated sheriff’s sergeant,” Dean said. “He died a hero. He went in to save lives.”

Long was also found dead inside the bar, and Dean said it’s believed he shot himself.

In addition to Helus, five others killed by Long have been named: Cody Coffman, Justin Meek, Alaina Housley, Noel Sparks and Sean Adler.

The sheriff estimated a dozen or more people were wounded; most of the injuries were minor things like scratches, scrapes and cuts that were sustained from jumping out of windows and diving under tables while trying to avoid the gunfire.

“It’s a horrific scene in there. There is blood everywhere and the suspect is part of that, and I didn’t want to get that close and disturb the scene and possibly disturb the investigation,” he said.

“We have no idea whether there is a terrorism link or not,” Dean said, adding there was no reason to believe there was, but they would look at that option.

He noted later that his department had several previous contacts with Long, most recently a call to his home in April, when deputies found him angry and acting irrationally because of what authorities said might have been post-traumatic stress disorder. A mental health crisis team was called at the time and concluded Long did not need to be taken into custody.

Other encounters included a traffic collision and a 2015 battery at a local bar in which Long was the victim, Dean said.

Witnessed described the gunman as tall and wearing all black with a hood over his head and his face partly covered.

It appeared he shot a security guard first before going inside, shooting at other security personnel and employees and then firing randomly in the bar, Dean said.

Patrons screamed in fear, shouted “Get down!” and fled to all corners of the bar, while a few people threw barstools through the second-story windows and helped dozens to escape, according to witnesses.

“It’s a horrific incident. It’s part of the horrors that are happening in our country and everywhere,” Dean said. “And I think it’s impossible to put any logic or sense into the senseless.”

The weapon used in the deadly shooting was designed in California to hold 10 rounds and one in the chamber, but it had an extended magazine, the sheriff said. It was unclear how many rounds were in the gun, which is still being processed as evidence.

The shooting took place as the bar was hosting its weekly “College Country Night,” and authorities said hundreds were inside when the gunfire erupted. Many were students, witnesses said.

The bar, which includes a large dance hall with a stage and a pool room along with several smaller areas for eating and drinking, is a popular hangout for students from nearby California Lutheran University. Classes were canceled there for the day following the shooting.

“It’s going to be a very somber day,” said Cal Lutheran Student Body President Nick Steinwender, who immediately went to the scene after receiving messages about the shooting. “I know we don’t have all the details in yet, but you know, it just feels like it’s an attack on our community. You know, I think it’s going to be something that we’re going to have to come together and move past.”

Other schools in the area include California State University Channel Islands in Camarillo, Pepperdine University in Malibu and Moorpark College in Moorpark.

Shootings of any kind are very rare in Thousand Oaks, a city of about 130,000 people about 40 miles west of Los Angeles.

It’s considered among the safest cities in the U.S., according to Mayor Andy Fox.

“We are consistently ranked one of the highest with respect to the lowest crime rate per capita,” he told CNN. “The reality is that these types of incidents can happen really at any place, at any time, even in communities that are considered extremely safe.”

A video posted to Instagram by witness Dallas Knap shows someone entering the bar moments before shots begin ringing out. A voice is then heard screaming, “Guys, run, go. He’s coming out this door.”

Text posted along with the video reads, “I looked him in his eyes while he killed my friends I hope he rots in hell for eternity. The guy you see is the murderer and the shots are him shooting people trying to get out the windows.”