Fallen sergeant, killed in California mass shooting, honored by first-responders

The gunman who killed 12 people at the Borderline Bar & Grill in Thousand Oaks, California, was a 28-year-old veteran of the Marine Corps who had previous run-ins with the law, officials said.

Here’s what we know about Ian David Long so far:

The gunman’s body was found in the bar

The shooter is dead, and his body was found inside the bar, police said. He was dead when police arrived on the scene, Ventura County Sheriff Geoff Dean said.

Dean said he believed that the gunman killed himself.

The gunman used one handgun

Dean said that officials found a Glock .45-caliber handgun at the scene that was purchased legally. The weapon usually holds 10 rounds, plus one in the chamber, but the gunman used an extended magazine in this shooting, Dean said.

Dean said he did not know of the shooter’s motive, and he did not know of any connection between Long and the Borderline bar.

The gunman had previous run-ins with the law

Police had several contacts with Long previously.

In April, officers responded to a disturbance at Long’s home, and he was somewhat irate and acting irrationally, Dean said. A mental health specialist met with him and ultimately decided not to detain him under laws pertaining to his mental health.

The gunman was on active duty with the US Marine Corps from August 2008 to March 2013, according to Defense Department records.

The gunman started firing suddenly

The gunman was dressed in black and wearing glasses when he walked into the bar filled with people enjoying a night of line dancing.

“I started hearing these big pops. Pop, pop, pop. There was probably three or four, I hit the ground,” John Hedge told CNN affiliate KABC.

Holden Harrah told CNN the gunman opened fire within seconds.

“This guy just came out of nowhere and came out with a gun and shot people in Thousand Oaks, California,” Harrah said. “And that’s what’s really blowing my mind, it’s a really safe area.”

Reports of the shooting came in around 11:20 p.m. PT.

“I heard a gunshot, I turned around and I saw him shoot a couple more times,” California Lutheran University student Teylor Whittler told KABC. “Within a split second, everybody yelled ‘get down,’ ” she said.

Witnesses said that people dropped to the floor and hid behind bar stools in stunned silence. Others jumped over chairs and broke windows to get out of the bar.

'He was shooting everything'

Witnesses described a man cloaked in black and wearing glasses as he walked onto a dance floor filled with people.

"I started hearing these big pops. Pop, pop, pop. There was probably three or four, I hit the ground," John Hedge, at the bar with his stepfather, told CNN affiliate KABC.

"I look up -- the security guard is dead. Well, I don't want to say he was dead, but he was shot."

Holden Harrah told CNN the gunman opened fire within seconds.

"This guy just came out of nowhere and came out with a gun and shot people in Thousand Oaks, California," Harrah said. "And that's what's really blowing my mind, it's a really safe area."

The gunfire started during line dancing, witnesses said. People dropped to the floor and hid behind bar stools in stunned silence. Others jumped over chairs and broke windows to get out.

When deputies arrived at the scene three minutes after the first 911 call, shots were still being fired, authorities said.

It was college night at the bar

The bar is near several colleges, and is a popular spot for students Wednesday nights. The Western-style bar hosts theme nights such as country, salsa and swing dancing.

On Wednesday night, students gathered for college country night between 9 p.m. and 2 a.m., according to the bar's website.

"I heard a gunshot, I turned around and I saw him shoot a couple more times," student Teylor Whittler told KABC.

"Within a split second, everybody yelled 'get down,' " she said.

People "dog-piled on top of each other" trying to hide in silence, she said. Some men ran toward them and said the gunman was coming. As they escaped through the bar's back door, she heard a second round of shots.

There was no screaming, she said -- just gunfire and stampeding crowds.

Nick Steinwender, who is part of the university's student government, said his friends were inside the bar when the shooting started.

"It was chaos, people jumping out of windows, hopping over gates and just trying to get out," he told the affiliate. "From what I heard, the gunman started shooting at the front desk. ... Students were hiding in the attics, bathrooms and stuff like that."

Pepperdine University said some of its students were at the bar, and it's working to identify them.

"The University offers its deepest condolences and is praying for everyone involved in tonight's tragic events," it tweeted.

City ranked one of the safest, mayor says

Thousand Oaks is in Ventura County, about 40 miles from downtown Los Angeles. The city "is considered one of the safest cities in the country," according to Mayor Andy Fox.

"We are consistently ranked one of the highest with respect to the lowest crime rate per capita. We're proud of that," Fox said.

"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."