A mechanical failure, specifically a problem with the main rotor, caused the fatal DPS helicopter crash in Flagstaff, according to a preliminary NTSB report.

A National Transportation Safety Board report released Tuesday shed more light on a crash involving an Arizona Department of Public Safety helicopter in Flagstaff that left two DPS crew members dead.

Add Yahoo as a preferred source to see more of our stories on Google. An Arizona Department of Public Safety pilot and paramedic trooper were killed in a helicopter crash after "numerous gunbattles" ...