SACRAMENTO, Calif. (Reuters) - This week’s fatal shooting of 12 people in a California bar by a Marine combat veteran came the day after the election of a new Democratic governor who has pushed for tighter gun control in the state, which already has some of the strictest firearms laws in the country.

Ian David Long, 28, used a .45 caliber Glock handgun equipped with a high-capacity magazine to mow down patrons late on Wednesday in the bar and dance hall filled with college students, authorities said.

The shooting raised questions about the efficacy of existing gun safety laws as Gavin Newsom, a two-term lieutenant governor closely aligned with gun control advocates, prepares to take the helm in the most populous U.S. state following his election victory on Tuesday.

“He’s been such a champion on this issue so we expect to see more innovation from the legislators and approved by Gavin Newsom,” said Laura Cutilletta, legal director of the Giffords Law Center to Prevent Gun Violence.

By “champion” she was referring to the former San Francisco mayor’s avid support of gun safety regulations,

Two years ago, Newsom co-authored a gun control ballot initiative that sought to extend the state’s ban on the sale and transfer of high-capacity magazines to include those owned before the original legislation, passed in 1999, went into effect. Those magazines were “grandfathered” into the law.

Newsom’s measure was challenged in a lawsuit supported by the National Rifle Association, and the courts put on hold the provision relating to high-capacity magazines.

FILE PHOTO: California Democratic gubernatorial candidate Gavin Newsom speaks after being elected governor of the state during an election night party in Los Angeles, California, U.S. November 6, 2018. REUTERS/Mike Blake/File Photo

Newsom on Thursday vowed to push for even stricter laws. Though he provided no specifics, he signaled a shift from outgoing Governor Jerry Brown, also a Democrat, who vetoed numerous gun control measures, including a bill to tighten the state’s law against assault weapons.

“The response is not just prayers,” the governor-elect said at a news conference on Thursday, referring to the shooting at the Borderline Bar and Grill in Thousand Oaks, 40 miles (64 km) northwest of Los Angeles.

“The response cannot just be excuses. The response sure as hell cannot be more guns.”

High-capacity magazines allow shooters to unleash prolonged torrents of bullets and reduce the need to re-load. Gun rights advocates have argued that such magazines help people defend their homes from intruders. But gun safety supporters say banning them would force perpetrators of mass shootings to pause and reload, creating an opening for law enforcement to respond.

It was not immediately clear how or when Long obtained his gun and magazine. He was a small child when California banned the sale of high-capacity magazines and would not have been able to legally own a gun or ammunition, said Chuck Michel, a lawyer representing gun owners challenging California’s ban.

Long, he said, could have easily gone to another state to purchase a high-capacity magazine for his Glock. He also could have stolen one.

Numerous other states, including Colorado, Connecticut, Hawaii, Maryland, Massachusetts, New Jersey, New York, Vermont, and Washington, D.C., ban the sale of high-capacity magazines, according to the Giffords website.

California requires background checks for gun purchasers, keeps records of transactions, and in January is set to begin background checks for purchasers of ammunition.

Earlier this year, officers went to Long’s home to answer a disturbance call and found him agitated, Ventura County Sheriff Geoff Dean said. Mental health specialists talked with Long and determined that no further action was necessary.

Still, Dean told reporters on Thursday that Long, who apparently killed himself in the bar, may have suffered from PTSD.

While Newsom on Thursday did not say what additional gun control measures he wanted to pursue, many gun rights advocates are bracing for an onslaught of new regulations under the incoming governor.

“Gavin Newsom has never met a gun ban he didn’t like,” Michel said.