Cervera said the shooter was armed with a gun with an attached sound suppressor and extended magazines, enabling him to fire many rounds and engage four police officers in what the chief described as a "longterm gunbattle" down building hallways.
"The officers stopped the suspect from doing more carnage in the building," Cervera said.
The chief said authorities will name the shooter, who according to a city spokesman worked in the public utilities department, only once. Thereafter, "he will be forever referred to as the suspect. Our focus is on the dignity to the victims in this case and their families."
Police had no immediate information as to a possible motive.
Mayor Bobby Dyer told reporters that "today is Virginia Beach's darkest hour." He said a "senseless crime happened and imposed tremendous grief upon the people of Virginia Beach, the Commonwealth and this country."
Gov. Ralph Northam said the victims, shot near the end of the last day of the week, "were heading into the summer weekend. That they should be taken in this matter is the worst kind of tragedy."
He added that the shooting, "tests our souls."
Friday's shooting added another city to the growing list of places affected by a mass shooting. It is the deadliest since November, when a gunman opened fire at the Borderline Bar & Grill in Thousand Oaks, California, killing 12 before fatally shooting himself. A police officer responding to that shooting died after suffering multiple gunshot wounds.
Virginia Beach, a resort city with an population of about 450,000, is the most populous city in the state. It has nearly twice as many residents as Richmond. The municipal center is a sprawling compound of more than 30 buildings and annexes that includes City Hall, courts and offices for multiple city departments, a city directory shows.
The three-story Building 2, where the shooting occurred, has workers who inspect properties, issue building permits, handle zoning issues and deal with the complex issues of public works, from trash pickup to water distribution.
"It's where all of our city business is located," City Councilman Aaron R. Rouse said.
Edward Weeden, an office assistant in Building 2, said he was at the first-floor reception desk when he heard a sound coming from the direction of a staircase. He and another employee went toward it and found a woman lying at the bottom of the steps, he said.
The woman was not responsive and was bloodied, Weeden said. One of his co-workers ran upstairs to check on what happened and fled back down, announcing that there was a shooter.
Weeden ran out of the building as law enforcement began to swarm. "I thank God for getting me out of that building," he said.
Megan Banton, who works in the building where the shooting occurred, said she was on the second floor when her supervisor heard a loud noise and told people to go into her office.
The sound of gunshots continued as about 20 people huddled on the floor after they barricaded the door with a desk. "We kept hearing gunfire," Banton said. "We were trying to keep as quiet as possible."
She said some people in the office were crying, while others appeared nervous and some remained silent.
Conditions of the surviving victims were not immediately available, and a precise count was not provided. Though police said four were in surgery, officials said there might be others. Hospital at Sentara Virginia Beach General Hospital reported two people in critical condition and two in fair condition. One patient at Sentara Norfolk General Hospital in critical condition.
Banton, the employee who was on the second floor of the public works building, said she has an 11-month-old baby boy and sheltered in the office wondering if she would ever see him again.
"You never think this is going to happen to you. When it happens to you, it's totally different," Banton said.
Sheila Cook, who was in the courthouse in the complex, told a local television news station she heard muffled gunshots but knew it wasn't in her building. She said police acted quickly to alert people that they were safe after the shooter had been apprehended.
"That was enough to make me feel safe enough to come outside, and that God was with us," she said. She added, "I'm feeling shaken and relieved at the same time."
Harold Gaskill, a supervisor in the permits and inspections office, was at home on his last day of a week-long vacation when news of the shooting broke. He said he spent the next two hours calling his workers and other colleagues to make sure they were okay. Everyone he knew made it through unharmed, he said.
Gaskill, 63, has worked for the city for 29 years. He said he works on the first floor of Building frequented by the public. He said he was told by co-workers that the shootings occurred on the second and third floors, where offices for public works and utilities are located.
"As far as I know, everyone in my office is okay," Gaskill said. He added that he has not learned names of the dead or injured, or that of the shooter. "It's just hard to believe right now," he said. "I don't understand it."
"There is no way to describe an incident such as this," Cervera said. "The suspect was immediately confronted . . . our citizens can rest easy tonight. We do not have someone out in the community to do more harm."