VIRGINIA BEACH, Va. (Reuters) - A disgruntled public utility employee opened fire with a handgun on co-workers at a municipal building in Virginia on Friday afternoon, killing 12 people and wounding at least four before he was fatally shot by police, authorities said.

The mass shooting in the coastal resort of Virginia Beach was the deadliest instance of U.S. gun violence since November 2018, when a dozen people were slain at a Los Angeles-area bar and grill by a gunman who then killed himself.

Virginia Beach Police Chief James Cervera said the suspect in Friday’s carnage was armed with a .45-caliber pistol equipped with a “sound suppressor” device and “extended” ammunition magazines he used to reload repeatedly during the attack.

Survivors recounted scenes of pandemonium and fear that erupted as gunshots rang out, and workers scurried frantically for cover.

“We just heard people yelling and screaming to get down,” Megan Banton, a public utilities worker, told television station WAVY-TV, recalling that she and co-workers barricaded themselves in their office.

“We put the desk up against the door because we didn’t know if they were coming in. We were just hoping that it would be over soon, and then we heard the cops yelling up the steps.”

The first victim was shot in a vehicle outside the public works and utilities building at the city municipal center before the suspect entered that building and “immediately and indiscriminately fired upon all the victims,” Cervera said.

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The chief said the suspect engaged in a “long-term gun battle” with four police officers who confronted him inside, preventing the gunman from “committing more carnage in that building.”

One officer was wounded in the shootout, but his bullet-proof vest saved his life, Cervera said. Authorities said the gunman ultimately was shot by police and was declared dead at a hospital.

‘MORE QUESTIONS THAN ANSWERS’

Cervera said the suspect was a longtime public utilities employee, and described him as “disgruntled,” but declined to say more about what may have precipitated the attack.

“We have more questions than we really have answers,” he told reporters about two hours after the shooting.

The shooting was believed to be the deadliest act of workplace gun violence in the United States since February, when a factory worker shot five colleagues to death in Aurora, Illinois, just after he was let go from his job.

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Authorities have determined the suspect’s identity but are not ready to make the name public, Cervera said.

“We will release his name once,” the chief said. “Then he will be forever referred to as ‘the suspect,’ because our focus now is on the dignity and respect of the victims and their families.”

The bloodshed unfolded, according to police, at Building Two of the municipal center complex, where office space for more than 400 employees houses information technology, public works, planning and utilities departments next door to City Hall.

The complex lies several miles inland from the town’s popular seashore, situated on the Atlantic coast at the mouth of the Chesapeake Bay. Southeast Virginia’s most populous city has roughly 450,000 year-round residents.

“This is the most devastating day in the history of Virginia Beach,” Mayor Bobby Dyer said at a news conference with the police chief. “The people involved are our friends, co-workers, neighbors, colleagues.”

Arriving in town a short time after the shooting, Virginia Governor Ralph Northam said: “This is just a horrific day.”

“Our hearts ache for victims of the senseless violence that has been inflicted on the community,” he told a news conference hours later.

In Washington, a White House spokesman said President Donald Trump had been briefed on the shooting and “continues to monitor the situation.”