THOUSAND OAKS, Calif. — Many witnesses who were inside the Borderline Bar and Grill for a college country event where 12 people were gunned down Wednesday night said the gunman, wearing all black and armed with a handgun, said nothing and started shooting as soon as he entered the club.

"We heard shots, I looked up and knew exactly what was happening. I tried to pull down as many people as I could," said Matthew Estron, who was at the Thousand Oaks, California bar for "college country night."

He said he didn't hear the gunman say anything. The shooter, who was later found dead of a gunshot wound, was identified by law enforcement officials as former Marine Ian David Long, 28, who served in Afghanistan and was an infantry machine gunner. He used a .45 caliber Glock handgun in Wednesday's shooting.

When Estron heard a pause in gunfire, he assessed the shooter must be reloading his gun, and took the opportunity to throw barstools at the windows in an effort to escape.

Others at the bar weren't as clear on what the sound was when the gunman came in and started shooting. And smoke permeating the inside of the popular hangout spot added to the confusion.

"You start hearing what almost sounds like firecrackers going off because somebody came in through the front door and just started shooting people the second he walked in," said Todd Stratton.

"I didn't really fully recognize that like it's an actual shooting, you know because you are in shock. You're trying to register the situation," Stratton said.

Once those who were able to escape spilled into the parking lot, the priority was finding their friends.

Sarah Rose DeSon was celebrating her friend's birthday when she heard the shots. She tried to find safety under a table, but there were too many people there, and "by the grace of God I got to the front door."

When she got outside and into a friend's car, she circled the parking lot in an effort to find another friend she had separated from.

"We weren’t going to leave our friend," she said, adding that she was found safe hiding in bushes.

Teylor Whittler said she came to Borderline with 10 other people. "We still don’t know where two of them are. We haven’t heard from them. Their parents haven’t heard from them. They haven’t gone home. We don’t, we don't know."

Matt Wennerstrom said he watched some of his friends "take fire," and two of them were unaccounted for.

"We’re all here still praying and just hoping to hear that they made it to a hospital or something and they’re receiving medical care, but I don’t believe that everyone made it out alive," he said.

The 20-year-old, who said he's been going to Borderline regularly for years, also heard some employees had been shot.

"It's a great place, and to see something like this happen to all the wonderful people that go here, the people that I consider basically family ... It's heartbreaking for me," Wennerstrom said.

"It's a horrific scene in there," said Ventura County Sheriff Geoff Dean during a news conference in the bar's parking lot. "There's blood everywhere."

Among those killed was responding Ventura County Sheriff's Office Sgt. Ron Helus, a 29-year police veteran with a wife and son who was looking to retire in the next year.

Helus, 54, arrived at the scene alongside a colleague from the California Highway Patrol within three minutes of reports of shots being fired at around 11:20 p.m. (2:20 a.m. ET Thursday), according to Dean.

About 10 to 12 other people were injured, according to police.

“There were just bodies on top of bodies, men crying and women screaming,” said Matthew Curry, 20, who was at the bar Wednesday night.

He said he believes a man his friend had introduced him to before the shooter walked in was killed. “He was some guy I just met … and then he was gone," Curry said.

Many who were at Borderline Bar, especially popular with college students on Wednesday nights, described it as a place where you run into friends you haven't seen in a while, along with people you see there every week.

Holden Harrah, 20, said he saw the woman working the front desk get shot. He assumes she was killed. "My eyes were directly on the target,” Harrah said. "Unfortunately I had to see a friend die."

Harrah said the bar is a place where students from nearby colleges, including California Lutheran University, Moorpark and Pepperdine University, come to catch up. He said he's made visits there part of his routine for half a year now.

The University has determined that multiple Pepperdine students were on site at Borderline Bar and Grill in Thousand Oaks. At this time, the University is working to identify and provide support to those students. (1/2) — Pepperdine University (@pepperdine) November 8, 2018

"The reason why I come, I like running into people I haven’t seen in a very long time," said the student. “It was a good night tonight. It hasn’t been packed recently, but tonight there was a good amount of people.”

"I’m very very lucky to be here. Very very lucky to be on my two feet," Harrah added.

He said he never expected such violence in his community. Thousand Oaks was ranked the third-safest city in the United States this year, according to the data analysis website Niche.

"Thousand Oaks, I like to say it’s our safe-haven because this type of stuff doesn’t happen, like ever," Harrah said. "No one would ever think this would happen here, and that’s why I’m in shock."

Richie Duchon reported from Thousand Oaks, California. Elisha Fieldstadt reported from New York.