The initial call came in at 6 a.m. regarding a home in the 7700 block of South Enchanted Spring Drive, about 17 miles southwest of Tucson.
Responding deputies found the male victim, later identified as TPD recruit Carlos Ramirez, dead and rushed the female to a hospital, where she was in stable condition, the sheriff said.
Ramirez also previously worked as a corrections officer in Pima County, according to two local law enforcement sources.
According to the Tucson Police Department, the 23-year-old was just days away from completing police academy training, set to graduate from the Southern Arizona Law Enforcement Training Center on Aug. 27.
"The Tucson Police Department is deeply saddened by the passing of Carlos Ramirez, a member of Basic Recruit Class 26-1," a spokesperson told Fox News Digital. "Carlos was fatally shot early this morning. His fiancée was also injured and is currently receiving medical care. Our thoughts are with Carlos's family and loved ones, his fiancée, and his classmates, instructors, and academy staff during this difficult time."
Tucson Police Chief Monica Prieto is asking anyone with information to call 911.
Prieto called it both a "tragic event and tremendous loss for ... our community, this city and our department."
Nanos said during a news briefing he expected to be briefed by detectives when more information is available.
A PCSD spokesperson said the shootings are not believed to be connected to the abduction of Nancy Guthrie, which took place on the other side of town at her home in Tucson's Catalina Foothills Feb. 1.
This is a developing story.