The alleged gunman in Virginia Beach used a legally purchased weapon suppressor

The utility engineer who allegedly shot dead 12 people, including 11 colleagues, at the Virginia Beach Civic Center, informed his boss that he was resigning a few hours before committing the massacre with legally-purchased pistols and a suppressor. of firearms, announced officials.

Investigators said DeWayne Craddock, 40, used two .45-caliber pistols, extensive ammunition magazines and a gun suppressor during the rampage. According to the investigators, the firearms and the suppressor were legally purchased by Craddock.

He bought one of the guns in 2016 and the other in 2018. He did not know exactly when he had bought the suppressor.

Virginia Beach Police Chief James Cervera told ABC News that the suppressor did not eliminate the sound of gunshots, but he could not tell if the use of the gun was so loud. This device had an impact on the number of deaths in Building 2 of the Virginia Beach Civic Center.

Two other weapons seized from Craddock's home were also legally purchased, officials said.

Sarah Holm // The Virginian Pilot via AP

In the brief resignation email, Craddock did not reveal anything of the horror that was expected to unfold Friday afternoon.

"I officially wish to put my (2) week notice to quit my engineering position at the City of Virginia Beach," wrote Craddock in his e-mail. "It was a pleasure to serve the city, but for personal reasons, I must take up my duties."

Craddock did not specify his personal problems.

The name of the person to whom the email was sent has been redacted by the officials. The e-mail recipient responded by telling Craddock: "I hope you can resolve your personal reasons. Let's be clear, your last day of work will be Friday, June 14, 2019."

Virginia Beach City Director Dave Hansen said Craddock was "in good standing" at work and had no problems with the discipline. Hansen said that the latest assessment of Craddock's work showed that he had a "satisfactory" performance.

Police investigating the massacre have not yet unveiled the motive of what might have caused the bloodshed. Craddock was killed after a long shooting with the police.

"We continue to speak with witnesses and other people who may hold information," a police spokesman told ABC News on Monday. "We are still only at the beginning of such an investigation.The additional details, if they are obtained, will be communicated once we reach a point where it will not at risk the investigation. "

Investigators said Craddock, a single person living alone, had worked as a utility engineer in Virginia Beach for 15 years.

Puce Somodevilla / Getty Images

Just after 4 pm on Friday, he reportedly burst. Craddock allegedly killed a victim outside the municipal building, then entered the four-storey building 2 and allegedly continued the massacre using his secure pass to sneak into the offices and interior conference rooms, said at ABC News Virginia Beach Police.

After killing five women and seven men, including a private contractor who was there to lay a license, Craddock engaged in a shootout with police who left him dead and injured a police officer.

On Sunday, police announced that the first calls for the shooting had occurred at 16:06. and that two officers arrived at Building 2 in two minutes, running from a police station on the other side of the street.

Five to 10 minutes after entering the building, at least four officers located the suspect and hired him on the second floor of the building.

The suspect fired as he was crossing many office spaces. During the shooting, the doors were closed and locked, and the people still on that floor were sheltering on the spot.

At one point, the gunman opened fire on police officers through a closed door. Once the gunfire subsided, the officers broke down the door and found the suspect fatally wounded.

Victims killed in the massacre have been identified as Richard Nettleton, a public service engineer for 24 years; Laquita C. Brown of Chesapeake, agent of public works for four and a half years; Tara Welch Gallagher of Virginia Beach, 6-year Public Works Engineer; Mary Louise Gayle of Virginia Beach, Public Works Engineer for 24 years and rights of way agent; Alexander Mikhail Gusev of Virginia Beach, employee of the public works for 9 years.

Katherine A. Nixon of Virginia Beach, a public utility engineer for 10 years, was also killed; Christopher Kelly Rapp, public works employee for 11 months; Ryan Keith Cox of Virginia Beach, a public service worker for 12 ½ years; Joshua O. Hardy of Virginia Beach, a public utility engineering technician for four and a half years; Michelle "Missy" Langer of Virginia Beach, Administrative Assistant to Public Works for 12 years; and Robert "Bobby" Williams of Chesapeake, coordinator of special projects for utilities for 41 years.

The independent subcontractor Herbert "Bert" Snelling, of Virginia Beach, who was at the municipal center to issue a permit, was also killed.

Puce Somodevilla / Getty Images

Four other victims were injured during the shooting and remained in hospital Monday in critical condition.

A memorial service for victims is scheduled for Thursday.

On Monday, hundreds of city employees resumed work for the first time since mass shooting. They were greeted by counselors and volunteers accompanied by therapy dogs.

Building 2 of the Civic Center remained closed and workers from the city gathered at the Virginia Beach Convention Center.

Hansen, the City Manager, spoke to employees, encouraging them to stay together and overcome the tragedy as a "family," said Michelle Walz, Supervisor of the City's Park Department, at WVEC-TV, a subsidiary of ABC, located in Norfolk, Virginia.