Flagstaff police are investigating a deadly officer-involved shooting that happened on Thursday night.Officers were called to a Walmart store on Huntington Avenue before 10 p.m. for reports of an armed man in the parking lot. When officers arrived, they called to the man who was sitting in a truck before he fired his weapon at officers.Police returned fire on the subject, killing him. He has since been identified as 29-year-old Flagstaff resident Sean D. Brady.Police later found two rifles, a handgun, boxes of ammunition and spent casings in his truck. Police also say he had earlier had brandished a gun during a verbal altercation with somebody else about the man playing loud music.EDITED SHORT VIDEO FROM DIFFERENT ANGLESSEPARATE VIDEOS