TONOPAH, Ariz. (KABC) -- An Arizona trooper trying to help a motorist in a rollover crash was shot in an ambush-style attack by a random suspect, who was then fatally shot by a Good Samaritan driving by.The trooper with the Arizona Department of Public Safety (DPS) was at a traffic stop when he received a report about a driver whose car was shot at near a median at milepost 81 on Interstate 10, reported ABC15 , an ABC affiliate in Arizona.The trooper left the traffic stop to investigate this call when he came across a rollover crash and saw that a woman had been ejected from the wreckage.When the trooper began working to block lanes, a suspect came from an unknown direction and "ambushed" him, according to DPS.The suspect shot him at least once in the chest-shoulder area and fought the trooper to the ground.A passerby saw the fight unfolding and stopped to render aid to the trooper, who asked for help.However, the suspect ignored the Good Samaritan's orders to stop attacking the trooper.That's when the passerby went to his car, grabbed a gun and fatally shot the suspect, reported ABC15.DPS said the injured trooper, who has been with the department for 27 years, was taken to an area hospital, where he was awaiting surgery. He is in stable condition.The woman who was ejected in the rollover crash died from her injuries, authorities said. The cause of the wreck was not known.DPS Col. Frank Milstead said he has yet to speak to the passerby, but he had this message for him:"Thank you because I don't know if my trooper would be alive today without your assistance."The incident was under investigation.