The Philadelphia club is the U.S. headquarters of the group, which has several locations in the Mid-Atlantic and Midwest regions.
An ex-member of the Wheels of Soul told the Daily News that the victims are believed to include the vice president of the club's Camden chapter and the national president's son. The ex-member said he'd heard that the shooter, a nonmember, had been beaten inside the clubhouse, then was kicked out and denied re-entry. He apparently waited outside.
"A couple of them guys in the club are thugs. You go in there, you're taking a risk. They ended up beating up that guy," he said. "But some guys aren't going to take that ass-whooping and walk away from it. They ran into the wrong one."
The ex-member said the victims had just returned from a member's funeral in Chicago and weren't involved in the altercation inside the building.
"They'd just pulled up from Chicago, not knowing that anything had transpired, and this is what happened," he said. "He was pissed off at the ones inside, so he just opened up on anyone that had Wheels of Soul colors on."
A man who said he has ridden with the club for years but declined to give his name said he had heard a similar version of events.
"The guy was sitting out front, and a few people came walking up the sidewalk and he started shooting at them," he said.
Police could not confirm what led to the shooting.
Investigators were still inside the clubhouse Sunday afternoon as yellow crime-scene tape blocked off the area. There was a motorcycle parked near the clubhouse entrance next to a pool of blood and a gray skullcap.
The group is well-known to police. One man was killed and a second man critically wounded last April during a shooting outside the same location.
Several people were arrested when FBI and Bureau of Alcohol, Tobacco, Firearms and Explosives agents raided the clubhouse in July 2011 as part of a sweeping racketeering indictment filed in St. Louis.
The indictment alleged that 18 members from seven states - Pennsylvania, Illinois, Ohio, Missouri, Colorado, Wisconsin and Kentucky - were involved in murder, kidnapping and the distribution of crack cocaine. None of the alleged murders or assaults occured in Philadelphia.
A resident on Dewey Street who declined to give her name Sunday said the violence is upsetting.
"They need to shut that s--- down. Somebody's always shooting over there," she said. "It's just too much. Why [aren't] they ever shutting it down for good?"
No arrests had been made Sunday night.
On Twitter: @ChroniclesofSol