A disgruntled veteran public utilities employee stormed a government building in the US State of Virginia and fired indiscriminately on multiple floors at his co-workers, killing at least 12 people and wounding six others, police said Saturday, in the latest incident of mass shooting in the country.

The suspect, a long-term and current Virginia Beach city employee, fired "indiscriminately" on multiple floors in a public utilities building, police said.

Police Chief James Cervera told reporters there was an exchange of gunfire with officers and a police officer whose ballistic vest stopped a bullet was injured.

The shooting suspect was identified as DeWayne Craddock, according to a law enforcement official and a Virginia government source, CNN reported.

Craddock, 40, worked as a certified professional engineer for the city of Virginia Beach in the Public Utilities Department. He is listed on department news releases as a point of contact for information on local road projects over the past several years.

"This is the most devastating day in the history of Virginia Beach. The people involved are our friends, coworkers, neighbour, colleagues," Mayor Bobby Dyer said.

The shooter was a disgruntled employee, the report said, quoting a Virginia government source.

"The President has been briefed on the shooting in Virginia Beach, VA and continues to monitor the situation," White House said.

"This is a horrific day for the Commonwealth of Virginia. We are devastated by the tragic shooting in Virginia Beach," said Virginia Governor Ralph Northam after visiting the scene.

The shooting took place shortly after 4 PM within the sprawling Virginia Beach Municipal Center, a campus of city offices and agencies, including the Police Department, when the gunman entered the public works department building of the city's municipal center.

The attack unfolded on multiple floors in Building No. 2, which includes offices for planning and public works, among others, and is adjacent to City Hall.

Police found victims on every floor of the building, the police chief said, adding the identities of the victims were not immediately released nor was the motive of the attack.

According to local Virginian Pilot newspaper, the shooter came armed with a .45-caliber handgun with a sound suppressor on it and shot one victim in a vehicle outside before entering the building. The rest were shot inside.

The FBI is helping the city police in investigating the shooting incident.

Senator Mark R Warner said that he is horrified by what has happened in Virginia Beach.

"I am thankful to law enforcement for their swift and courageous response. My heart goes out to all the victims of today's senseless violence, their families, and the entire community that has been affected by these awful events. I will be praying for the swift recovery of those injured," he said.

"My heart breaks for Virginia Beach. For the victims, their families, the community, everyone impacted by this terrible act of violence. But the moment we resign ourselves to be just onlookers to such carnage, we lose our soul. We can and will take action," Senator Ed Markey said.

The incident is the deadliest mass shooting in the US since November.

Twelve people were killed at the Borderline Bar & Grill in Thousand Oaks, California in November.

Officials said that gunman shot an unarmed security guard outside the bar, went in and continued shooting, injuring other security workers, employees and patrons.

(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)