PHILADELPHIA — A man was fatally shot outside a Philadelphia concert being held to promote peace and stem violence in the city, police said Thursday.

The shooting happened at about 8:30 p.m. Wednesday outside the Dell Music Center in the city's Fairmount Park, according to investigators.

Officials said the 20-year-old man was apparently either arriving at or leaving the "Philly Support Philly: Peace on the Streets" concert when he got into an argument with someone in the parking lot.

Police said the shooter opened fire, striking the victim twice. He was rushed to Temple University Hospital, where authorities said he was pronounced dead at about 2:15 a.m. Thursday.

No arrests have been made. Police said they are checking surveillance video.

The concert featuring rap music was attended by about 600 people. No other injuries were reported.

Police commissioner Charles Ramsey told reporters that such a shooting outside an event aimed at stemming violence comes as no surprise.

"People who put on these concerts are well-intentioned," Ramsey said. "The problem is, it doesn't always reach the street thugs that we deal with on a daily basis. This is what they do, and they don't care if it's at a peace rally, in church — they could care less."

"So I'm not frustrated and I'm not surprised," he said.