It happened around 10:45 p.m. Sunday on the 1400 block of Surrey Lane near Haverford Road, which isn't far from City Avenue.
Neighbors told Action News they heard at least eight gunshots and police taped off a house on the block.
Lower Merion police said when officers arrived they found Nahray Mumakk Crisden, 19, of Philadelphia's Overbrook section, with multiple gunshot wounds. He was pronounced dead at the scene.
The owner of the house said she didn't know Crisden. Many neighbors also said they didn't know of anyone on the block who may have been connected to the victim.
Crisden was a football and track star. His mom says he was her best friend and when she got the call that he had been shot, it almost killed her too.
"That boy was my best friend and he had my whole entire heart," said Rashala Hill.
Hill said he was the fastest kid in school and they dreamed of his future.
"I told him...one day, you're destined, you're destined for greatness. You're a king, act like one," said HIll
Officers brought in a K-9 from Radnor Police to assist in the search for the gunman.
Neighbors said they heard a helicopter and saw a searchlight being used shortly after the shooting.
Now as a police look for a killer, Hill has a message for whoever shot her child.
"Whoever killed my son. They don't know they killed me too. I will never be OK. I will never be OK," said HIll.
Montgomery County Detectives and Lower Merion Police launched a joint investigation. An autopsy is scheduled for later Monday at the Montgomery County Coroner's Office.
Anyone with information is asked to contact the Lower Merion Township Police at 610-649-1000 or Montgomery County Detectives at 610-278-3368.