Arizona Department of Public Safety officials have identified the trooper who was shot and wounded along Interstate 10 west of Phoenix.
They say Edward Andersson is hospitalized in serious but stable condition after the incident early Thursday.
The 27-year department veteran underwent surgery for gunshot wounds to the right shoulder and chest.
A suspect fought with the trooper before being fatally shot by a driver who stopped to help.
Authorities say a possible motive for the attack on the trooper remains unclear.
The shooting occurred at the scene of a rollover crash in which a woman was ejected and fatally injured.
DPS officials say Andersson spotted the wreck as he responded to a report of shots being fired at another motorist's vehicle.