The stabbing happened Monday around 4 p.m. in the 1500-block of Hanover Street in Chicago Heights, police said.
Officers found two boys, 14 and 13 years old, with apparent stab wounds. Both were taken to a local hospital.
RELATED: 2 teenage boys stabbed in Chicago Heights, police say
David Sanchez, 13, died from his injuries on Tuesday at a hospital, according to the medical examiner.
There is no update on the 14-year-old's condition.
Chicago Heights police and Illinois State Police Crime Scene Services are investigating.
Chicago Heights police asked anyone with information to contact them at 708-756-6400.
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