The Brief A Flagstaff police officer was involved in a fatal two-vehicle collision on East Butler Avenue. The Arizona Department of Public Safety will investigate the cause of the crash. A Flagstaff police officer was involved in a deadly crash on the morning of Sept. 20. What we know:An officer with the Flagstaff Police Department was involved in a collision with another vehicle on East Bulter Avenue near the Sinagua Heights intersection around 7:30 a.m. What's next:The Arizona Department of Public Safety will conduct the crash investigation, while the police department's Professional Standards Unit will conduct an internal review.