 SOURCES TELL CBS NEWS THAT THIS IS BEING INVESTIGATED BY THE SECRET SERVICE. THE SECRET SERVICE HAS CONFIRMED THAT THEY ARE WORKING WITH THE FBI AND TREATING THIS AS AN ATTEMPTED ASSASSINATION OF A CANDIDATE. THE SHOOTER WHO CARRIED OUT THIS ATTACK WAS SHOT AND KILLED BY THE SECRET SERVICE. AND WE KNOW THAT SOURCES ARE TELLING CBS NEWS THAT THE GUNMAN WAS ON A SHED USING AN AR-STYLE RIFLE.