Troy Fletcher, 15, is charged with murder and related offenses. He is currently a fugitive.
Police are also still searching for 16-year-old Dayron Burney-Thorn, who is also charged with murder.
Anyone with information on the whereabouts of either Fletcher or Burney-Thorn should contact Philadelphia police.
Two suspects have been arrested in this case.
Yaaseen Blivins, 21, and Zyhied Jones, 17, were arrested earlier this week.
The fatal shooting happened on September 27 around 4:30 p.m. on the 4700 block of Pechin Street just as a junior varsity football scrimmage ended between three schools: Roxborough High School, Northeast High School and Boys Latin Charter School.
Theshooting killed 14-year-old Nicolas Elizalde of Havertown, Pa. and left four other teenagers wounded.
Elizalde was a freshman at Saul High School but played football for Roxborough.
Police have said Elizalde is not believed to have been one of the intended targets.
According to investigators, the suspects waited for six minutes before jumping out of the SUV and firing more than 60 shots.
A $45,000 reward has been offered for information leading to an arrest or conviction.
The Associated Press contributed to this report.