12 killed after gunman opens fire 'indiscriminately' at Virginia Beach office: Police Four injured victims were also admitted to area hospitals.

A city worker opened fire "indiscriminately" at the Municipal Center in Virginia Beach Friday afternoon, killing at least 12 people before he was shot dead by police in a "long gun battle," police said.

Eleven of the victims died on the scene and one succumbed to their injuries on the way to the hospital, Virginia Beach Police Chief James Cervera said during a press conference Friday night.

An additional four victims were in surgery at local hospitals for their injuries and "others may have self-transported," Cervera said.

Two law enforcement sources confirmed to ABC News that DeWayne Craddock, 40, is the alleged suspect in the shooting.

Virginia Beach city manager Dave Hansen said that Craddock was an active city employee, but declined to say if he had recently been disciplined or was the subject of complaints to human resources.

Police said Sunday that Craddock was not terminated for his job nor was he in the process of being terminated. Authorities are still investigating a possible motive.

Three of the injured patients were at Sentara Virginia Beach General Hospital, with two in critical condition and one in fair condition. Another patient was at Sentara Norfolk General Hospital in critical condition, according to Dale Gauding, senior communications adviser for brand engagement at Sentara Healthcare

One of the injured victims is a Virginia Beach police officer who was saved by his bulletproof vest, Cervera said.

The suspect, who had access to the Municipal Center as a public utilities employee, walked into the building at around 4 p.m. and began to "indiscriminately fire upon all the victims," Cervera said. There were victims on all three floors of the building, and one outside, who Cervera said was shot before the suspect entered the building.

The suspect had two firearms — a long gun and a handgun — law enforcement sources told ABC News.

Four officers responded to the shooting and engaged in a "long gun battle" with the suspect, eventually shooting him, Cervera said, noting that the officers likely "stopped the suspect from committing more carnage."

Responding officers also secured as many victims as they could, Cervera said.

A .45-caliber handgun was found with multiple empty magazines following shootout, Cervera said.

"We just heard that there was an active shooter and we just barricaded ourselves in offices to make sure that we were all safe and I called 911 just to get them to come there as fast as possible," said Megan Banton, a Public Works employee who was on the second floor of the building. "My boss was like, 'This is not a drill. Get down, call 911.'"

Officials are in the process of identifying the victims, Cervara said, adding that their names would be released once all of their family members were notified.

"This is the most the most devastating day in the history of Virginia Beach," said Virginia Beach Mayor Bobby Dyer.

Virginia Gov. Ralph Northam described the shooting as "unspeakable, senseless violence."

"My deepest condolences and prayers go to the families of those who left home this morning and will not return tonight, as well as those who have been injured in this tragedy," Northam said.

Authorities are asking people to avoid the Municipal Center area. The scene is now secure but it is still active, Cervera said.

The FBI, the Department of Homeland Security and Virginia State Police are assisting in the investigation.

Cervera described the shooting as a "devastating incident" that "will change a lot of lives."

"I just don't know why anyone would do something like that," Banton said. "I don't know what would possess someone to come in and start shooting at people."

ABC News' Alexander Mallin contributed to this report.