One person is dead after a three-vehicle crash near 29th Street and Harrison Road.
When the Tucson Fire Department arrived on scene, they found an adult female unresponsive in her vehicle.
That women was transported to Banner University Medical Center, where she was later pronounced dead.
She has been identified as 60-year-old Elizabeth Steele.
Two other occupants in one of the vehicles were transported to Tucson Medical Center with minor injuries. The driver of the third vehicle involved had minor injuries, as well - but, did not need to be taken to the hospital.
Detectives with the Tucson Police Department Traffic Investigations Unit were able to determine that an adult female driver of a red 2006 Toyota 4Runner was traveling southbound on Harrison Road when she stopped at a red light at 29th Street.
Then, an adult male with a juvenile female passenger in a blue 1999 Dodge Dakota pulled up behind the Toyota.
Then, investigators say - Steele struck them from behind in a silver 2013 Hyundai. The force pushed the Dodge into the back of the Toyota.
Speed does not appear to be a factor.
Detectives are still investigating if there were any impairments or a medical issue with Steele.
Steele was also not wearing a seatbelt.