The Pima County Sheriff's Department has identified a man and woman killed in separate Tuesday morning collisions, authorities said.
Nikolas Roberts, 22, was killed in the first crash, which took place at about 3 a.m., in the area of North Swan Road and East Sunrise Drive, said Deputy Ryan Inglett, a Pima County Sheriff's Department spokesman.
Roberts's car was traveling south on Swan when it drove over the median and rolled. The male driver was pronounced dead at the scene, Inglett said.
Roberts was wearing his seatbelt, but speed is believed to be a factor in the crash.
It's unknown when the second crash took place, but a sheriff's deputy discovered a vehicle near Old Tucson at about 6:30 a.m., Inglett said.
The deputy found 18-year-old Katalina Arellano in the vehicle, which had gone off the roadway in the area of North Kinney Road and West McCain Loop. Arellano was airlifted to Banner-University Medical Center Tucson where she was later pronounced dead.
Arellano was not wearing her seatbelt, and speed is also believed to be a factor in the crash, Inglett said.