The call came in at 12:37 p.m. Wednesday. A 21-year old gunman, clad in a T-shirt that bore the image of four scythe-wielding grim reapers on horseback, wanted the police to know that he had just opened fire in a bank in the small city of Sebring, Fla., the police said. “I have shot five people,” he told a dispatcher, according to a police statement. There were only five people in the bank at the time, the police said, and they all died. When the Sebring Police Department and the Highlands...