The boy is charged with one felony count of first-degree murder and one felony count of attempted first-degree murder, according to Chicago police.
The victims, 15 and 17, were in the backyard of a home about 1:15 a.m. in the 6800 block of South Peoria Street when the 14-year-old opened fire, Chicago police said.
The 17-year-old was shot in the chest and was taken to the University of Chicago Medical Center, where he was pronounced dead, police said.
The other, 15, was struck in the stomach and taken to the same hospital in serious condition, police said.
The Sun-Times Media Wire contributed to this report.