Lewis said the victims were outside of a residence when they were approached by two people.
One of those people fired a gun at the victims striking both of them before fleeing with the other person.
Both victims were transported to hospitals and the 17-year-old was later pronounced dead. He has been identified as Carlos Villareal.
The 15-year-old suffered a critical injury but is expected to survive.
Police have not arrested any suspects.
The investigation is ongoing.
Anyone with information about this crime should call the Phoenix Police Department or Silent Witness at 480-WITNESS (480-948-6377) or for Spanish (480) TESTIGO. Callers may remain anonymous and could earn a reward of up to $1,000.