Relatives of victims mourn the death of bar shooting rampage at Los Robles Medical Center in Ventura County, California, the United States, on Nov. 8, 2018. (Xinhua/Qian Weizhong)

THOUSAND OAKS, the United States, Nov. 9 (Xinhua) -- Hundreds of people gathered Thursday at a vigil here to mourn the victims of a mass shooting on Wednesday night, which has killed 13 including a sheriff's deputy.

Thousand Oaks, ranked the third safest city in the United States in 2018 by website Niche, was added to the list of victims of gun violence in a country divided over its gun policies.

BLOOD EVERYWHERE

A U.S. Marine veteran opened fire in the Borderline Bar and Grill, which is popular with college students, in Thousand Oaks, a suburb about 64 km northwest of Los Angeles, law enforcement officials said.

Local authorities identified 28-year-old Ian David Long as the gunman of the mass shooting, who was found dead of an apparently self-inflicted gunshot wound afterwards.

Ventura County Sheriff Geoff Dean said Long, a former machine gunner and Afghanistan war veteran, apparently fired at random with a 45-caliber Glock handgun with an extra-capacity magazine inside the bar at about 11:30 p.m. local time Wednesday (0730 GMT, Thursday).

"The weapon was designed in California to hold a magazine of 10 rounds and one in the chamber, but he had an extended magazine on it," the sheriff told a news conference on Thursday morning.

According to witnesses at the scene, the shooter threw a smoke grenade into the bar before opening fire with a handgun.

Madison Cummings, an eyewitness at the bar, told Xinhua that the shooter had a beard and short black hair, wore all black and held a black handgun.

"At the first sight, I thought it was a joke, because the music did not stop. But later I smelled the gun fire, then I knew it's real," she said.

Deputy Sgt. Ron Helus went into the bar with another highway patrol officer after they received calls about the shooting. Helus was shot several times in confrontation with the shooter and died in hospital later, Dean said.

Authorities said hundreds of people were inside the bar when the gunfire rang out.

"It's a horrific scene in there," Dean said. "There is blood everywhere."

WAR TRAUMA FEARED

Paul Delacourt, assistant director in charge of the Los Angeles FBI, told a news conference Thursday afternoon that it was too early to speculate on the motive for the massacre but that the shooter appeared to have acted alone.

Dean described Long as "acting a little irrationally" when police were called to his home earlier this year to investigate a disturbance. He lived in Newbury Park, near Thousand Oaks.

In the neighborhood where Long lived, residents said they were well aware of his problems. Richard Berge, 77, was quoted by local media as saying the former Marine had post-traumatic stress disorder (PTSD) and was known to kick in the walls of his home.

Garo Kuredjia, captain of Ventura County Sheriff office, told Xinhua he could not confirm the shooter's PTSD, and did not know what his medical or mental status was.

"I can assume he has some sort of mental issue, because no normal person would commit such an outrageous act and murder innocent people," Kuredjia said.

Tami Teece, a survivor of the mass shooting in Las Vegas last year that killed 59 people and wounded more than 500 others, was among the crowd mourning the death of Helus along the road.

Teece, who also has PTSD, told Xinhua that the government should spend more money setting up mental hospitals for veterans to address their psychological problems.

FESTERING PROBLEM

The California bar shooting was the second mass killing in two weeks to hit the United States, home to more than 300 million guns scattered nationwide and long plagued by gun violence.

Less than two weeks ago, 11 worshippers were killed by a gunman at a synagogue in Pittsburgh, Pennsylvania.

The United States has one of the highest gun-related death tolls in the world due to lax gun control laws, according to a study released in August by the Institute for Health Metrics and Evaluation at the University of Washington.

According to the Gun Violence Archive, a U.S. non-profit corporation providing gun-related violence information, 307 mass shootings have occurred this year.

America has been torn apart by this politically divisive issue.

In an unprecedented move in recent U.S. history, thousands of high school students walked out of class across the country in March in a call on Congress to pass tighter gun-control laws.

Earlier in May, U.S. President Donald Trump reiterated his strong support for gun rights during a speech in the city of Dallas, Texas.

"Your Second Amendment rights are under siege but they will never ever be under siege as long as I am your president," Trump said at the National Rifles Association (NRA) annual meeting in the convention center in Dallas.

The U.S. failure to bring down gun-related violence and the murder rate is a result of multiple factors, according to experts.

For one thing, with the vast and growing gap between liberals and conservatives, and Democrats and Republicans, gun control has become an increasingly partisan issue, with Republicans more uniformly opposed.

It also involves the powerful gun lobby, largely led by the NRA, one of America's richest and most influential lobbying groups.

America's electoral structure also lends NRA supporters outsize influence, as many gun-rights advocates live in rural areas where a few votes can swing a congressional election, experts said.

(Xinhua correspondent Tan Jingjing also contributed to the report.)

(Video reporter: Tan Yixiao; video editor: Wang?Anhaowei)