By Ashley Loose, KNXV

TONOPAH, Ariz. -- (KNXV) -- The Arizona Department of Public Safety is investigating after a trooper was shot while responding to another call near Tonopah early Thursday morning.

The incident occurred after 4 a.m. on westbound I-10 west of Tonopah.

According to DPS Col. Frank Milstead, a citizen called to report that their vehicle was shot at from the median near milepost 81 on Interstate 10.

A trooper in the area left another traffic stop nearby to investigate the call when he came upon a rollover crash near milepost 89. He saw a woman who had been ejected from the crash and began working to block lanes.

At that time, DPS says the trooper was “ambushed” by a suspect who came from an unknown direction. The suspect shot the trooper at least once in the chest-shoulder area and fought the trooper to the ground.

A passerby stopped to render aid and the trooper asked for help. Officials say the driver went back to his car, grabbed a gun and shot at the suspect who was not following his commands to stop attacking the trooper. The suspect was killed.

Milstead has a message for the motorist who shot the suspect and called on the trooper's radio for help.

"Thank you," Milstead said, "because I don't know if my trooper would be alive today without his assistance."

DPS says the injured trooper, who has been with the department for 27 years, was taken to the hospital where he is awaiting surgery. He is in stable condition.

The woman thrown from the rolled-over vehicle also reportedly died from her injuries. Officials have yet to determine what caused the vehicle to rollover.

Col. Milstead says he hasn’t talked to the passerby who shot the suspect, but says “thank you because I don’t know if my trooper would be alive today without your assistance.”

DPS says the trooper was awake and talking prior to going into surgery. His wife is with him at the hospital. DPS says the trooper is currently assigned to the agency's commercial vehicle squad. Officials have not released his name.

DPS is still investigating.

FULL STORY: DPS trooper ambushed, shot on Interstate 10 in Tonopah - KNXV