Pima County Sheriff's deputies responded to an injured pedestrian struck by a vehicle on Alvernon Way near Interstate 10 Wednesday evening.
The pedestrian was taken to a hospital with serious injuries, said Deputy Daniel Jelineo, a department spokesman.
Detectives determined the pedestrian was not in a crosswalk as they attempted to cross Alvernon before the crash, Jelineo said.
The driver stayed on scene to cooperate with detectives. Neither speed nor impairments appear to be factors in the crash.
Motorists are still experiencing delays while authorities are on scene.
Drivers are asked to avoid the area.
No further information has been released.
