The victim is identified as 20-year-old Alexis Guevera of Frankford.
The shooting happened at 8:30 p.m. Wednesday outside the concert facility at 33rd Street and Huntingdon Avenue in Fairmount Park.
Guevara died Thursday morning at the hospital after he was shot twice Wednesday night in the Dell's parking lot.
On Thursday night, Guevara's mother and sister flew in from Tennessee and went to their hometown block of Phillips Street in Olney.
"I just need the person, whoever did this, to come forward. I want justice to be served. I want him to feel our pain," said Dolly Guevara, sister.
Family and friends huddled together in prayer.
Dolly says her brother had a job at Macy's and planned to attend college in the fall.
"He loved the people around him, didn't want to get into trouble - he wasn't that type of person," she said.
Surveillance video shows the suspected shooter and an accomplice in the parking lot of the Dell.
They are seen harassing people, and eventually two shots are fired.
Both shots hit Guevara, one in the stomach and one in the thigh.
The suspects then fled in a white Chevy Impala.
The concert called, 'Philly Support Philly: Peace on the Streets,' was sponsored by Philadelphia's Parks and Recreation Department.
Organizers say the idea came from a group of teens who wanted to raise money for the Borum family.
Last month, 3-year-old Tynirah Borum was shot and killed by a stray bullet.
Cyrina Cupit says Guevara lived in Frankford but was raised in Olney. She saw him right before he left to go to the concert.
"This is why he's got all this love out here. Everybody came to show him love and sign candles and everything for him," said Cupit.
Meanwhile, police are looking for the gunman and an accomplice who sped off in a white Chevy Impala.
The alleged gunman was wearing a black t-shirt with a distinctive logo and blue jeans.
Anyone with information about the case is asked to contact Philadelphia Police at 215-686-TIPS (8477), text a tip to PPD TIP (773847) or through PhillyPolice.com.