NORRISTOWN, Pa. – Authorities in Montgomery County say a teenager shot and killed a 15-year-old in Norristown Wednesday night.

Alex Herrera, 16, of Norristown, is charged with First-Degree Murder, Third-Degree Murder, Firearm Not to be Carried Without a License, Possession of a Firearm by a Minor and Possessing an Instrument of Crime, the Montgomery County District Attorney’s Office said in a news release.

The DA’s office said the killing happened shortly after 8:30 p.m. Wednesday in Haws Alley off of George Street.

Norristown Police found the 15-year-old lying in the alley suffering from a gunshot wound to the head, the DA’s office said. He was taken to a trauma center, where he was pronounced dead, according to authorities.

The investigation found that two groups of juveniles met three times that night to engage in a fight but kept having to change locations due to police presence, according to the DA’s office.

The third fight ended in the fatal shooting of J.O., the DA’s office said.

The DA’s office said detectives recovered one .40 caliber live round and one .40 caliber fired cartridge casing at the scene.

Detectives also recovered a cellphone on scene, later determined to belong to Herrera, the DA’s office said.

According to the DA’s office, detectives found multiple publicly posted videos from the area of the shooting that showed numerous juveniles running from the scene after the shot was fired.

Detectives identified Herrera, who appeared to be holding something in his waistband as he ran from the scene, authorities said.

The DA’s office said Norristown Police stopped Herrara near the shooting scene.

According to the DA’s office, Herrera is awaiting arraignment at the Montgomery County Youth Center. A preliminary hearing will be scheduled at arraignment.