The suspect has been identified as 17-year-old Michael Nixon. He is being charged as an adult with murder.
"We're here today talking about a tragedy that should have never happened," said police superintendent Timothy Bernhardt.
The victim, Khalief Webster, was shot around 3 p.m. Sunday near Long Lane and Pine Street. The scene is not far from Webster's home.
Police say there was an argument before Webster was shot in the back.
Detectives quickly narrowed in on a suspect.
"Late Monday, we knew who we were looking for. We knew we were looking for 17-year-old Michael Nixon of Upper Darby Township," said Bernhardt.
Investigators would not say Webster and Nixon knew each other before the shooting, but both were students at Upper Darby High School.
Police say Nixon surrendered to police Tuesday night after investigators had spoken to family and executed two search warrants trying to track him down.
"We've got to figure out another way to resolve conflict. Guns are not the answer and it's just senseless, it breaks my heart," said Mayor Ed Brown.
Webster's family told Action News that he loved playing sports in the neighborhood with his siblings and friends. They also said he loved to work, holding several jobs, and couldn't wait to join the workforce full-time.
"When I see the news and clips on social media of young men being gunned down, I sit there and I mourn for their parents," Webster's mother, Talaya Shaw, told Action News this week. "Now, I'm mourning my son."
"Two families have been shattered," said Bernhardt. "And Khalief Websterwill never get to enjoy life. Will never get to go to college. Will never get to have a family. Will never get to do all the things he should've been able to do if it wasn't for the cowardly act of Michael Nixon."
Police say more charges could be coming in this case against the individuals they say hid Nixon from police after the crime.