VIRGINIA BEACH — Virginia Beach employees went back to work Tuesday at their campuslike municipal complex, many girding themselves for their first official day back after one of their colleagues shot and killed 11 co-workers and a contractor who had come to take out a building permit Friday afternoon.

“I feel numb and hypersensitive,” said Sarah Deal Jenkins 55, a deputy city clerk. “My nerves are a little on edge.”

She was not alone. Men and women, clutching bags, backpacks and purses, walked slowly to their offices as the workday began, many waiting until 5 minutes before the official starting time. Some bowed their heads in prayer.

“I’m hanging in there,” said Debbie Spivey, a receptionist in the city attorney’s office. “It’s just devastating, and I’m numb.”

Authorities said DeWayne Craddock, 40, walked into the public works building Friday afternoon and used two .45-caliber pistols to shoot and kill a dozen people and injure others. A sound suppressor, or silencer, was found at the scene as well as extended magazines for the weapons, police have said.

Craddock died in a gunfight with police.

Authorities are still searching for a motive. Craddock has been described as an ordinary employee with no pending discipline issues. Hours before the mass shooting, he had submitted a short resignation letter to his bosses.

In that resignation email, he called his time working for the city a “pleasure” and said he would be leaving his job with the city’s Department of Public Utilities in two weeks. Craddock, who was a longtime engineer for the city, wrote that he was leaving “due to personal reasons,” but did not elaborate.

Some colleagues who knew Craddock said they saw no sign of what was to come.

“I knew him very well,” said Velma Mills, a retired city employee who is working as a contractor for the Virginia Beach treasurer’s office. “That was not him. He was a quiet person, very polite.”

Officials have said that both of the weapons Craddock used in the shooting were purchased legally, one in 2016 and one in 2018. On Tuesday, Officer Linda Kuehn of the Virginia Beach Police Department said a silencer found at the shooting scene was also bought legally but said she did not know when or where it was purchased.

Police said an extended magazine was used on at least one of the guns Craddock fired in the attack, but declined to say how many rounds it held. Two other firearms were found in Craddock’s residence, one purchased legally, officials said over the weekend, with no additional information publicly released on the other.

Craddock had worked for Virginia Beach for nine years and “was in good standing within his department,” City Manager Dave Hansen said, with “no issues of discipline ongoing.” The city originally said he had worked for about 15 years for Virginia Beach.

Newport News officials said Tuesday that he worked as an engineer there from November 2008 to January 2010. Before Newport News, Craddock worked for two private engineering firms beginning in 2003, officials with those firms said.

Divorce files from 2017 showed Craddock lived alone and had no children in his nine-year marriage.

Spivey recalled Tuesday that she had left her receptionist job Friday at 4:09 p.m., just before the lockdown, unaware of the shooting. She didn’t know what had happened until her phone blew up with calls, including from her boss, who had to know exactly where she was.

“This has touched me immensely,” Spivey said Tuesday. She knew six of the employees who were killed.

On Tuesday, Gov. Ralph Northam (D) called for a special session of the General Assembly to debate a package of gun-control bills.

Authorities identified those killed as Virginia Beach residents Michelle “Missy” Langer, Ryan Keith Cox, Tara Welch Gallagher, Mary Louise Gayle, Alexander Mikhail Gusev, Katherine A. Nixon, Joshua O. Hardy and Herbert “Bert” Snelling; Chesapeake residents Laquita C. Brown and Robert “Bobby” Williams; Norfolk resident Richard H. Nettleton; and Powhatan resident Christopher Kelly Rapp.

At the municipal complex Tuesday morning, a growing makeshift memorial included flowers and 12 crosses to honor the victims. Building 2, where the shooting occurred, remains closed.

Michelle Bailey-Pittman, 39, an accounts payable clerk, made it as far as the bench outside Building 1 before she had to stop and call a colleague to walk her inside her workplace of 19 years. “This always felt like a safe place to me,” she said.

Her desk window faces the Building 2 parking lot. At 4 p.m. Friday, her mother, a retired city employee, was bringing two of Bailey-Pittman’s children to her office when they got caught in the lockdown and were ushered into another building.

“We were all hiding out. When we were in here I was scared for my life,” Bailey-Pittman said. “Now I’m going through a round of guilt.”

As she spoke, she clutched a rock she painted that said “5/31/19. Always Remember.” She had made it as part of a city employee event Monday, and planned to put it on her office windowsill.

“We pay the bills for all the departments and you work with people from everywhere,” she said. “On Saturday, to be quite honest, once I heard all the names of the people I knew on that list, I did literally nothing.”

She went to church Sunday and was comforted to see other city employees there.

“I’m so grateful I was able to go home to my family, but there are all these other families who don’t have theirs,” she began, her words trailing off as a friend approached.

They hugged long and hard, then walked slowly up the stairs to their building and paused for several long minutes. But it was nearly 8 a.m., starting time.