At least 12 people were killed in Virginia Beach, Virginia, on Friday when a gunman opened fire at a municipal centre, sending employees scrambling for cover before police fatally shot and killed him, authorities said.

Several others were wounded in the shooting. According to Virginia Beach Police Chief James Cervera, a veteran employee of the Public Utilities Department, entered the municipal centre and “immediately began to indiscriminately fire upon all of the victims”.

Cervera said police identified the attacker but would not disclose his name until authorities could reach family members.

“We’re going to mention his name once and then he will be forever referred to as the suspect,” he said.

Police entered the building and got out as many employees as they could, then exchanged fire with the suspect, who was killed, the chief said.

Cervera added the suspect was armed with a .45-caliber handgun equipped with a “sound suppressor” device and was reloading his weapon with extended ammunition magazines as he moved through the building.

The city’s mayor, Bobby Dyer, called it “the most devastating day in the history of Virginia Beach”.

A public works employee told a local NBC television news affiliate that employees were at their desks when gunshots rang out and recounted seeing a badly injured woman in a stairwell, WAVY-TV reported on its website.

Megan Banton, an administrative assistant who works in the building where the shooting happened, said she heard gunshots, called 911 and barricaded herself and about 20 colleagues inside an office, pushing a desk against a door.

“We tried to do everything we could to keep everybody safe,” she said. “We were all just terrified. It felt like it wasn’t real, like we were in a dream. You are just terrified because all you can hear is the gunshots.”

Virginia Governor Ralph Northam said in a statement he was devastated by the “unspeakable, senseless violence”, and is offering the state’s full support to survivors and relatives of the victims. The White House said President Donald Trump had been briefed and was monitoring the situation.

The precise circumstances of Friday’s shooting were being investigated, with FBI agents and Homeland Security Department forensic technicians assisting local police due to the “size and scope and intensity” of the crime scene, Cervera said.

The police chief 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.

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

150 mass shootings

Friday’s shooting was believed to be one of the deadliest acts of workplace gun violence in the United States. In February, a factory worker shot five colleagues to death in Aurora, Illinois, just after he was let go from his job.

The Gun Violence Archive website has documented at least 150 mass shootings so far in 2019. The monitor has also documented at least 5,764 people killed and 11,060 injured by gun-related incidents since January 1.

The US House of Representatives approved two bills in February to toughen background checks for gun purchases, but the legislation faces opposition from the Republican-controlled Senate and the White House.

They were the first major gun control measures approved in Congress in years.

Although Republican President Trump has said he supports stronger background checks, he has thus far toed the party line on gun control legislation, leaving Washington deadlocked on how to address frequent mass shootings in the US.

In December, however, the Trump administration banned bump stocks, devices that make semi-automatic weapons fire faster.