A disgruntled worker who went on a shooting rampage hours after being sacked killed 12 people, before he was shot himself.
Nine people were also injured in the horrific attack - including a police sergeant - in Virginia Beach, US.
The "long-serving employee" who fired "indiscriminately" at his former colleagues as he went from floor to floor.
The incident, which happened in the state of Virginia just after 4pm local time, has been described as "the most devastating day in the history" of the city.
Local news report said the gunman has been identified as DeWayne Craddock, according to a law enforcement official and a Virginia government source.
Craddock, 40, worked as a certified professional engineer at the Public Utilities Department for the city of Virginia Beach, CNN reports.
Officials recovered two guns, a rifle and a .45 caliber handgun, along with an extended magazine and a suppressor at the scene believed to be used in the shooting, it is reported.
Police earlier confirmed they were responding to reports of an “active situation” at the city's Public Works Department in a municipal center close to Virginia Beach.
The building was put on lockdown, according to local media, as emergency services, armed police and the FBI swarmed the area.
Virginia Beach Police Chief Jim Cervera earlier confirmed at a press conference tonight that 11 people - and the gunman - had died.
Victims, some the gunman's colleagues, were taken to hospital.
Chief James Cervera said the precise circumstances of the shooting in the coastal resort city remained under investigation.
He gave few details of what was known, but said a police officer was among those who were struck by gunfire but
survived.
Cervera said the suspect was a longtime current municipal employee, and described him as "disgruntled."
It was not made immediately clear whether the gunman took his own life or was killed in an exchange of gunfire with police.
The shooting unfolded, according to Cervera, at Building Two of the municipal center complex, a facility which houses the city's public works and utilities next door to City Hall.
"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."
The police officer who was shot was saved by his bullet-proof vest. He is understood to be a sergeant who has been with department for more than a decade.
"There's no way to describe an incident such as this," Chief Cervera said.
Andy Fox from WAVY news also tweeted: "I heard from a source that the shooter is a former employee who was actually fired yesterday from the city.
"The source also said that the number dead is around 12. Latest died at Sentara Norfolk General.
"We had been told the shooter died as well."
One witness named Edward was in the building when he was told to evacuate as there was a gunman on the loose.
He saw a woman with blood pouring from her face as she sat on a stairway.
He said: "She could have been shot, who knows."
Meanwhile, Virginia Beach Police tweeted earlier: "ACTIVE SHOOTER SITUATION-municipal center, building 2. Multiple injuries. At this time it is believed that only 1 shooter, and they have been taken into custody. More to follow."
People were also seen coming out the building crying and holding each other.
A woman at the scene claimed on Twitter: "There’s an active shooter situation occurring right now and all of the cops in Virginia Beach are flying down Nimmo Parkway there’s an officer that has been shot currently at the Post Office on George Mason.
"There is a shooter still shooting through a door on the third floor of what I'm assuming is the apartments behind Harris Teeter by the courthouse. Multiple shooting victims in the area.
"SWAT just arrived trying to secure the area. Apparently this shooter got multiple victims and is still shooting. 6 VICTIMS. 1 SURVIVOR.
"I’m watching the cop cars fly past me while I’m listening to this happen over the radio. They’re trying to clear the area.
"One man has a GSW [gun shot wound] to the face, is still alive. Multiple hiding in stairwells. Officers are still rushing to scene."
She later added: "They have the shooter on the ground.
"I can’t believe something this insane is happening so close to my house, let alone in the municipal center at the courthouse."
Congresswoman Elaine Luria tweeted: "My heart is with all those injured & affected by today’s shooting at the Virginia Beach Municipal Center.
"I’m so thankful for first responders & law enforcement for risking their lives to bring a suspect into custody. This is more proof Congress must act to prevent gun violence."
American rapper Pharrell Williams also shared his heartache but vowed the city would "come out of this stronger".
He said: "We are praying for our city, the lives that were lost, their families and everyone affected.
"We are resilient. We will not only get through this but we’ll come out of this stronger than before we always do."
Virginia Beach, which sits on the Atlantic coast at the mouth of the Chesapeake Bay, is the state's most populous city
with roughly 450,000 year-round residents.
