A FORMER roommate of the man authorities believe used a smoke bomb and a handgun to kill 12 people at a country music bar in Southern California, has described the suspect as a loner, who liked to ride motorbikes and listen to dance music.

Blake Winnett told Los Angeles Times he had lived with Ian David Long, 28, for about two years after they met in 2013.

“He wasn’t outgoing or talkative … He kept to himself, always had his earbuds in. He went to the gym, went to class, or rode his motorcycle,” Mr Winnett said.

He told The Times he had often tried to get Long to go out with him but “he never wanted to go.”

He said Long would hang out in the garage for hours and listen to dance music while dancing alone.

He claimed Long also used MDMA and was taking painkillers to treat a motorcycle related injury.

Despite his roommate’s lone wolf lifestyle, he said Long was dating a girl when they lived together and his mum came to visit him.

Long is suspected of killing a dozen people as he sent hundreds fleeing in terror during the shooting in Ventura County’s Thousand Oaks.

The gunman then apparently took his own life — according to authorities.

The attacker’s motive is unclear but Long is said to have been an Afghanistan war veteran who had been divorced and showed signs of post-traumatic stress disorder.

He was a former machine gunner who was interviewed by police at his home last spring after an episode of agitated behaviour that they were told might be PTSD.

MDMA has been successfully trialed as a treatment for PTSD in the US recently.

The former combat veteran was hooded and dressed in all black when he opened fire during the college dance.

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Screaming in fear, patrons rushed for the exits, dived under tables and used barstools to smash second-floor windows and jump to safety as gunfire reverberated through the Borderline Bar & Grill, a hangout popular with students from nearby California Lutheran University.

Authorities say five off-duty police were inside the venue when gunfire erupted.

Ventura County Sheriff’s Office Capt. Garo Kuredjian said two officers from the city of Oxnard and three from Los Angeles “assisted in evacuating those that were injured” and helped prevent others from being hurt.

‘THERE’S BLOOD EVERYWHERE’

“I dropped to the floor,” Sarah Rose DeSon told ABC’s Good Morning America. “A friend yelled, ‘Everybody down!’ We were hiding behind tables trying to keep ourselves covered.” The dead included 11 people inside the bar and a veteran sheriff’s sergeant who was the first officer inside the door, Ventura County Sheriff Geoff Dean said.

“It’s a horrific scene in there,” Dean said in the parking lot. “There’s blood everywhere.”

All morning, people looking for missing friends and relatives arrived at a community centre where authorities and counsellors were informing the next-of-kin of those who died. Many walked past TV cameras with blank stares or tears in their eyes. In the parking lot, people comforted each other with a pat on the back.

Brendan Kelly found himself in a terrifying and familiar scene when bullets started flying.

Like several others who were at the bar, Kelly is a survivor of last year’s massacre in Las Vegas, which killed 58 people.

Kelly, 22, said he was dancing with friends when the gunfire started.

Kelly, a Marine, was able to escape out the back with friends. He says God will never give him more than he can handle and that he’s “here for a reason.”

‘I LOVE YOU, SON’

Jason Coffman received the news that his son Cody, 22, who was about to join the army, was dead.

Mr Coffman broke down as he told reporters how his last words to his son as he went out that night were not to drink and drive and that he loved him.

“Oh, Cody, I love you, son,” Mr Coffman sobbed.

The bloodshed was the latest in what seems to be a never-ending string of mass shootings that are happening with terrifying frequency across the United States.

Pepperdine University says 16 of its students were at the bar during the attack. One of its students has been confirmed killed and two other students were treated and released from a hospital.

Another school in the area — California Lutheran University — confirmed that one of its recent graduates also was killed.

DEADLIEST SHOOTING SINCE PARKLAND

It was the nation’s deadliest such attack since 17 students and teachers were killed at a Parkland, Florida, high school nine months ago. It also came less than two weeks after a gunman massacred 11 people at a synagogue in Pittsburgh.

Democratic Gov.-elect Gavin Newsom, in his first public appearance since winning office on Tuesday, lamented the violence that has come again to California.

“It’s a gun culture. It’s a culture, and it’s not about being Democrat or Republican,” he said. “You can’t go to a bar or nightclub? You can’t go to church or synagogue? It’s insane is the only way to describe it. The normalisation, that’s the only way I can describe it. It’s become normalised.”

President Donald Trump praised police for their “great bravery” in the attack and ordered flags flown at half-staff in honour of the victims. Long was armed with a Glock 21, a .45-caliber pistol designed to hold 10 rounds plus one in the chamber, according to the sheriff. But it had an extended magazine — one capable of holding more ammunition — that is illegal in California, Dean said.

COPS RAID SHOOTER’S HOME

Authorities converged on Long’s home in Newbury Park, about 8km from the Borderline bar, in a search for clues to what set him off.

“There’s no indication that he targeted the employees. We haven’t found any correlation,” the sheriff said.

“Maybe there was a motive for this particular night, but we have no information leading to that at all.” Long was in the Marines from 2008 to 2013, rose to the rank of corporal and served in Afghanistan in 2010-11, the military said. Court records show he married in 2009 and was divorced in 2013.

Authorities said he had no criminal record, but in April officers were called to his home, where deputies found him angry and acting irrationally. The sheriff said officers were told he might have PTSD because of his military service. A mental health specialist met with him and didn’t feel he needed to be hospitalised.

NEIGHBOUR HAD CALLED POLICE ON ATTACKER

Tom Hanson, 70, who lives next door to Long and his mother, said he called the police about six months ago when he heard “heavy-duty banging” and shouting coming from the Longs’ home.

“I was concerned because I knew he had been in the military,” he said. Hanson said the sheriff’s deputy who arrived took his information, but he never learned more about what happened and hadn’t spoken to Long since then. He said he was “dumbfounded” by the bloodshed.

The gunman first shot a security guard standing outside, then went in and opened fire on staff members and patrons, the sheriff said.

A couple living behind the shooter’s house said he frequently had loud and aggressive arguments with his mother.

Don and Effie MacLeod said in an interview Thursday they heard what sounded like a gunshot from the house during a night-time argument about 18 months ago but did not call police.

The MacLeods have lived in the Newbury Park neighbourhood since 1983. Don MacLeod says Colleen Long moved in about 12 years ago and that Ian Long lived in the house on and off.

The MacLeods say they saw Colleen Long walking her dogs around the neighbourhood and that they often chatted with her.

But Don MacLeod says he avoided speaking with Ian Long because of his body language.

“The first I saw the guy I figured out, keep your distance,” he said.

The MacLeods said the arguments seemed to get worse within the last year.

HERO COP KILLED IN SHOOTING

Sheriff’s Sgt. Ron Helus and a passing highway patrolman arrived around 11:20pm in response to several 911 calls, heard gunfire and went inside, the sheriff said. Helus was immediately shot, Dean said.

The highway patrolman pulled Helus out, then waited as a SWAT team and scores more officers arrived. Helus died at a hospital.

By the time officers entered the bar again, the gunfire had stopped, according to the sheriff. They found 12 people dead inside, including the gunman, who was discovered in an office and had apparently shot himself, the sheriff said.

“There’s no doubt that they saved lives by going in there and engaging with the suspect,” said Dean, who was set to retire on Friday.

Helus was a 29-year veteran of the force with a wife and son and planned to retire in the coming year, said the sheriff, choking back tears.

He praised the slain officer — a close friend — as a hero: “He went in there to save people and paid the ultimate price.”

One other person was wounded by gunfire, and as many as 15 others suffered minor injuries from jumping out windows or diving under tables, authorities said. People at the bar fled from all exits, broke through windows and hid in the attic and bathrooms, the sheriff said. He said they seemed to know what to do.

“Unfortunately our young people, people at nightclubs, have learned that this may happen, and they think about that. Fortunately it helped save a lot of lives that they fled the scene so rapidly,” he said.

Around midday, the body of the slain sheriff’s officer was taken by motorcade from the hospital to the coroner’s office. Thousands of people stood along the route or pulled over in their vehicles to watch the hearse pass.

Firefighters paid tribute by using two ladder trucks to raise a giant American flag over the route.

SHOOTINGS RARE IN AREA

Shootings of any kind are extremely rare in Thousand Oaks, a city of about 130,000 people about 64km from Los Angeles, just across the county line.

The Borderline, which has a large dance hall along with several smaller areas for eating and drinking, was holding one of its regular “College Country Nights.” Nick Steinwender, Cal Lutheran student body president, told KTLA-TV he immediately started receiving messages about the shooting, and he and his roommate went to the scene to offer rides back to campus or moral support. “It’s going to be a very sombre day,” Steinwender said.

“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.”

The bar is also close to several other universities, including California State University Channel Islands in Camarillo, Pepperdine University in Malibu and Moorpark College in Moorpark.

Cole Knapp, a freshman at Moorpark, said he was inside the bar when the shooting began, but thought at first that it was “just someone with an M-80, just kind of playing a prank.” Then he said he saw the gunman, wearing a small black head covering and black hoodie.

“I tried to get as many people to cover as I could,” Knapp said. “There was an exit right next to me, so I went through that. That exit leads to a patio where people smoke. People out there didn’t really know what was going on. There’s a fence right there so I said, ‘Everyone get over the fence as quickly as you can,’ and I followed them over.” He said he had friends who were unaccounted for.

Tayler Whitler, 19, said she was on the dance floor when she saw the gunman shooting and heard screams of “Get down!” “It looked like he knew what he was doing,” Whitler told KABC-TV.