DALLAS (AP) — An Army veteran killed by Dallas police after the sniper slayings of five officers amassed a personal arsenal at his suburban home, including bomb-making materials, bulletproof vests, rifles, ammunition and a journal of combat tactics, authorities said Friday. The man identified as 25-year-old Micah Johnson told authorities he was upset about the fatal police shootings of two black men earlier this week and wanted to exterminate whites, "especially white officers," officials said. He was killed by a robot-delivered bomb after the shootings, which marked the deadliest day for U.S. law enforcement since the Sept. 11, 2001, terrorist attacks.