The Virginia Beach gunman appeared to target supervisors in his department in the early moments of a shooting spree that left 12 people dead on Friday, according to a survivor of the attack and a city councilman.
Authorities in Virginia Beach say they are still working to determine what motivated DeWayne Craddock to bring two handguns into his municipal office last week and begin shooting.
In the meantime, the survivor and the councilman described how Craddock walked down a hallway past a number of employees on the second floor of Building 2 before firing his first shots inside of the building, in an area where senior engineers and supervisors sat.
"He was looking for specific people apparently, at least at first," said Louis Jones, a Virginia Beach councilman and former mayor whose grandson, Jack Jones, was interning in the public works department and working on the second floor when the shooting occurred.
Craddock, a longtime engineer in the city's Department of Public Utilities, submitted a short letter of resignation the morning of the shooting. He wrote that he was giving his two weeks' notice "due to personal reasons," and that "it has been a pleasure to serve the City," according to a copy of the email released by the city on Monday.
City Manager Dave Hansen said on Sunday that questions around Craddock's employment status were part of the continuing investigation, but that Craddock had not been fired before Friday, and that there were "no issues of discipline ongoing."
The city redacted the names of the person or people Craddock sent the email to. But a colleague of Craddock's told CNN that Richard Nettleton, a 28-year employee of the city who was killed in that back office area, received the letter.
Jones, the councilman, said that his grandson was alone in an office on the second floor just after 4 p.m. on Friday when the gunman came to the door, looked at him, and then turned around, proceeding farther down the hallway.
Soon after, Jones said his grandson heard a first shot fired. The 21-year-old is being credited for potentially saving lives as he ran down the hallway screaming "gun, gun, gun," and "everybody get out," the councilman said in an interview.
Mike, an engineer who worked in Building 2 who would only give CNN his first name, said that he and his colleagues were first alerted to danger by a woman's scream from the back part of the second floor, where the engineering supervisors sat.
"I heard a scream and we all started going toward the scream. And then we heard gun shots," he said.
Nettleton and Katherine Nixon, both longtime engineers with the city and supervisors in the public utilities department, sat in the back area of the second floor hallway. They were killed in the shooting.
Nixon was not in Craddock's chain of command, according to a city official.
Randy Allen, another supervisor of the gunman's, was not injured during the shooting, according to a city official. It's not clear where Allen was at the time of the shooting.
Allen declined to comment to CNN when reached over the weekend.
Another official, Stephen Motley, is listed on the city's organizational chart as a Utility Engineering Manager in the Department of Public Utilities. CNN has reached out to Motley for comment.
Four people were hospitalized after the shooting. They have not been identified.
On Friday, in the first news conference after the shooting -- a time when details in an investigation are still usually fluid -- Virginia Beach Police Chief James Cervera said Craddock entered the building shortly after 4 p.m. and "immediately began to indiscriminately fire upon all the victims."
In subsequent news conferences, however, Cervera has declined to comment when asked if the shooter had targeted any victims. On Tuesday, a spokeswoman for the Virginia Beach Police Department said she could not discuss the ongoing investigation.
Authorities have interviewed city employees who survived the shooting as they've worked to piece together the gunman's movements inside the building, according to police.
Before entering the building Friday afternoon, Craddock shot and killed a contractor sitting in a car parked outside, authorities said. Craddock used two handguns in the shooting, one of which was equipped with a suppressor, which witnesses said dampened the sound of the gunfire.
Even after beginning his rampage, Craddock appeared to spare some city workers he came across, while shooting others.
Ned Carlstrom, who works in the billing section of the city's water department, told CNN affiliate WRAL that he crossed paths with the gunman three times and walked out of the building physically unharmed.
"We passed by a gentleman that was carrying a gun in his hand, but it looked so theatrical because of the extended magazine and the suppressor that was on the end of it," Carlstrom said. "He glanced at me, but he never raised the gun at me to shoot me."
Authorities have said that victims were found on multiple floors of the four-story municipal building, which includes a basement.
Another city worker who survived the shooting, Christi DeWar, described huddling in an office that she and her coworkers had barricaded with a metal filing cabinet.
DeWar said that she heard Craddock walking around on what sounded like the first floor of the building. According to DeWar, a colleague taking cover with DeWar later said she was texting with someone on the third floor who had heard the gunman there.
Four police officers encountered Craddock on the building's second floor about seven to ten minutes after responders were first dispatched to reports of an active shooter, according to Cervera, the police chief.
Cervera said the officers engaged the gunman in a long shootout through numerous office spaces before he barricaded himself in a room on the second floor.
"They realized the need to enter that office so that he would not then escape and perpetrate more violence on that second floor, so they had to figure a way to breach the door in a tactically safe and sound way. That's not an easy decision to make," Cervera said.
The officers breached the door and found Craddock inside, shot but still alive, Cervera said. As is their training, Cervera said, the officers then began to immediately render aid on the gunman, although he died soon after.