This post has been updated.

Just days before he would have finished his junior year of high school, a 17-year-old boy was violently gunned down in South Philadelphia's Southwark neighborhood Thursday night.

Police said they were looking into the possibility that the bullet that went through the boy's forehead, killing him instantly, had hit him by accident when a friend of his returned fire during a shootout that spanned more than a block of 5th Street.

About 15 shots rang out on 5th Street near Pierce shortly before 10 p.m., investigators said. The teen, identified by relatives at the scene as Nasir Westbrook, was pronounced dead where he fell onto the pavement at 10 p.m.

Police said they found shell casings fired from two different weapons at the scene and that the entire shooting was captured on surveillance footage outside a store on 5th Street.

One suspect in the homicide was in custody Thursday night and taken to be questioned by detectives, but police said they were still trying to determine whether he was the gunman who fired the shot that killed Westbrook, and that they did not recover a weapon from the suspect.

Investigators at the scene said the teen was unarmed when he was fatally wounded. No one else was hit.

"Take him to the hospital, give him some hope," a woman who identified herself as a relative of the boy but wished to remain anonymous said as she looked down 5th Street at Westbrook's sheet-draped body on the sidewalk.

Relatives and friends of the teen said he was a junior at a Mastery Charter school and a skilled boxer.

"He boxes all day. He's a good kid," another woman said of Westbrook. "He's a good kid. He probably was just in the wrong place at the wrong time."

Investigators said a surveillance camera outside a store on 5th Street near Pierce captured the entire shooting. They were reviewing that footage late Thursday night.

Meanwhile, just before 10:30 p.m., police said two men walked into Methodist Hospital with gunshot wounds and reported that they'd been shot near 8th and Jackson streets, about six blocks southwest of the homicide scene. A third victim in that shooting drove himself to Thomas Jefferson University Hospital.

In that shooting, police said an 18-year-old man was hit once in the back, a 28-year-old man suffered a graze wound to the chest and a 25-year-old man sustained gunshot wounds to his left thigh and calf. All three were in stable condition later Thursday evening.

Investigators were unsure what motivated the shooting and said the victims were uncooperative when asked to provide information about the incident. Ten 9mm shell casings and marijuana were found at that scene, police said. There were no witnesses and cameras did not capture the incident, police said.

Police said it was unclear whether the homicide and the triple shooting were related, but said that preliminarily, they did not find any evidence linking the two.

The South Philadelphia shootings were two of four shootings in which six people were wounded within about an hour and a half Thursday night. A man was critically wounded when he was shot in the head in Olney shortly after 10 p.m., and another man was hospitalized after being shot in the foot in North Philadelphia after 11 p.m.