VIRGINIA BEACH — The resignation email arrived in the morning, and the gunfire started in the afternoon. DeWayne Craddock, an engineer who had worked for the City of Virginia Beach for about 15 years, notified his superiors on Friday that he intended to quit. Then at around 4 p.m., he embarked on a rampage in Building No. 2 of the Virginia Beach Municipal Center, turning its offices and corridors into a battleground. When it was over, 12 people...