Passing driver kills gunman who ambushed Arizona trooper

PHOENIX -- A man who shot and wounded an Arizona state trooper Thursday along a remote highway and then started slamming the helpless officer’s head into the pavement as the two struggled was shot to death by a passing driver, authorities said.Trooper Edward Andersson, a 27-year veteran of the Department of Public Safety, was shot in the right shoulder and chest in what authorities called an ambush and was in serious but stable condition after surgery at a Goodyear hospital.DPS Director Fr