Virginia Beach, Virginia (CNN) The family of the gunman who killed 12 people at a Virginia Beach municipal building posted a handwritten message Saturday on their front door sending their "heartfelt condolences to the victims."

"We are grieving the loss of our loved one. At this time we wish to focus on the victims and the lives (lost) during yesterday's tragic event," they wrote. "Our thoughts and prayers are with the families of those who (lost) their lives, and those recovering in the hospital. -- The Craddocks"

A representative for the family of DeWayne Craddock declined to speak with CNN when reached by phone.

Authorities said the gunman shot one person in a car on Friday before entering the facility and firing at people on all three above-ground floors. He was killed after a fierce gun battle with four police officers

Several other people were wounded, including a police officer whose ballistic vest saved him from a .45-caliber bullet fired by the gunman. Three people were in critical condition, while one was in fair condition, hospital officials said Saturday.

The injured police officer was treated and released Friday. Police Chief James Cervera said he visited with the officer at his house Saturday and he was doing well.

'Why did this happen?' city asks

Crime scene tape stretched across the street Saturday near the back entrance of a Virginia Beach Municipal building where a day before a city employee shot and killed 12 people, including some of his colleagues.

A large FBI truck was parked outside Building 2, and investigators huddled near the back entrance of the building. Most of them were from the FBI, which has 40 agents there to manage evidence collection.

Virginia State police were stationed around the perimeter of the crime scene, keeping curious people out and also helping workers who returned to get their cars.

A couple, members of the nearby United Methodist Church, came to not only pay their respects, but to donate treats for the investigators who are in the early stages of trying to figure out why the shooter, a certified professional engineer in the city's public utilities department, went on a killing spree in his workplace.

The dozens of gunshots Friday sent terrified witnesses running out of the building or hiding under desks , authorities said.

"It's still a sense of shock, disbelief. Why did this happen?" Bobby Dyer, mayor of the coastal Virginia city, told CNN.

"I guess the big question is, why? We want to know, too."

Many deceased victims were longtime city workers

Friday's massacre is the deadliest in the United States this year and adds the city to a grim list of places impacted by a deadly mass shooting.

City Manager Dave Hansen said 11 city employees were killed. One had worked in Virginia Beach for 41 years.

They were Virginia Beach residents Tara Welch Gallagher, Mary Louise Gayle, Alexander Mikhail Gusev, Katherine A. Nixon, Ryan Keith Cox, Joshua O. Hardy, Michelle "Missy" Langer; Chesapeake residents Laquita C. Brown and Robert "Bobby" Williams; Norfolk resident Richard H. Nettleton; and Powhatan resident Christopher Kelly Rapp.

Also killed was a contractor, Herbert "Bert" Snelling, of Virginia Beach.

The city government said it will hold a remembrance event for the slain victims at 7 p.m. Thursday at Rock Church.

Shooter had security pass

Authorities identified the gunman as Craddock, a 40-year-old city worker who was a certified professional engineer and had worked in the city's public utilities department for about 15 years.

He had a security pass "like all employees had" to access inner offices of the building, beyond the public service desk near the entrance, Hansen said. That area is not accessible to non-employees.

The gunman is listed on department news releases as a point of contact for information on local road projects over the past several years.

Bureau of Alcohol, Tobacco, Firearms and Explosives Special Agent in Charge Ashan Benedict told reporters two .45-caliber pistols were found at the scene. Both were legally purchased, one in 2016 and one in 2018.

On Friday, authorities indicated one pistol had a suppressor and that several empty extended magazines, which could hold more rounds than a standard magazine, were found near the shooter.

A rifle also was found at the shooting site, according to a law enforcement official. Cervera has declined to comment about the presence of a rifle and Benedict didn't mention a rifle in his comments.

Investigators found "additional weapons" at the gunman's home, the chief said.

Cervera, the police chief, said his investigators still don't know the shooter's motive. He and Hansen declined to answer questions Saturday about whether the gunman had threatened anyone in the building previously or faced discipline at work.

Co-worker saw Craddock 'brushing his teeth like he always did' at work earlier

Joseph Scott, who said he worked with the shooter for several years, saw him in a bathroom at work Friday.

"He was at the sink, brushing his teeth like he always did," Scott told CNN. "I used the bathroom and walked up and was washing my hands, and I said, 'How are you doing?' He said he was doing OK.

"I asked, 'Any plans for the weekend?' And he said, 'No.' And I said, 'Well, have a good day,' and he said the same to me.

"And it was no more than that."

Scott said the gunman was "what I thought was a good person," and described him as generally quiet.

"When we were together, we would talk about family, friends, things that we were going to do, trips we were going to take and things like that," Scott said.

A Virginia government source briefed on the investigation told CNN the shooter was a "disgruntled employee."

The shooter's parents, reached Friday night, told CNN they weren't aware of any trouble that he was having with his employer.

Before he worked for the city, a Virginia-based engineering firm hired the gunman in 2003 as a project manager. An article in a business newspaper that mentioned the hiring said he held a bachelor's degree in civil engineering from Old Dominion University in Norfolk.

According to Virginia's Department of Professional and Occupational Regulation, the gunman obtained his certified professional engineer license in the state in 2008. The license wasn't set to expire until June 2020.

President pledges support

Gov. Ralph Northam ordered all Virginia flags to be lowered to half-staff across the state until sunset on June 8 in memory of the victims, according to the Virginia Capitol Police

In his first public comments on the shooting Saturday, President Donald Trump said he had called Northam and Virginia Beach's mayor and vice mayor to offer condolences.

"The Federal Government is there, and will be, for whatever they may need. God bless the families and all!" Trump said in a tweet

Correction: A previous version of this story misstated a victim's name. It is Joshua O. Hardy.