A heckler pointed a gun at Okafor's head following a verbal exchange in October at a Philadelphia club, the Inquirer reported, citing five sources who spoke on the condition of anonymity.
There is no known report of the incident and Okafor declined to address it, according to the Inquirer report. However, a source told the newspaper that federal officers witnessed the encounter.
A source close to Okafor told ESPN's Jeff Goodman that Thursday's altercation was prompted by taunting about the 76ers' dismal record.
"Apparently they said, 'The 76ers suck and you guys are all losers. You'll never win a game,'" the source said.
"I was around the corner when it happened. I saw [Okafor] a minute after he knocked the dude out. I think the guy was just talking s---. Saying the Sixers suck."
However, a police report gave a different account of Thursday's incident.
According to a statement issued Friday evening by Boston police, a man filed a police report Friday morning stating he was the victim of assault and battery outside the Storyville nightclub on Exeter Street in Boston at around 2 a.m. Thursday. The man said Okafor and another man approached his group and asked some of the women for their phone numbers. When the women declined, a verbal altercation ensued, followed by a physical scuffle. The man said Okafor pushed him and punched him, knocking him to the ground and causing a cut over his eye that later required stitches.
Police said they are "actively reviewing" the case and no charges have been filed. Police had said earlier Friday that they would not investigate the case unless someone involved came forward to say they were the victim of a crime.
Okafor, 19, addressed the Boston incident with reporters earlier Friday.
"It was definitely dumb on my part," Okafor said. "It's something that I am embarrassed about. [I'm] still dealing with the league and the team. But I'm not happy about it at all."
TMZ released video Thursday that showed a man it identified as Okafor verbally sparring with several individuals. A scuffle broke out, and the man identified as Okafor is seen punching a man.
"It doesn't happen often," Okafor said of being heckled, according to the Inquirer. "People are just coming after me, heckling, making fun of me for losing. It's something that I have known I'm in the spotlight.
"I know that there are people like that that try to anger you. I'll never handle it like [I did Thursday morning] again."
Okafor, who was with teammate Christian Wood at the time, said he spoke to Sixers coach Brett Brown about the incident Thursday. The 76ers released a statement Thursday evening saying they were aware of the report and working to gather additional information. An NBA spokesman also said Friday that the league was aware of and looking into the matter.
"We ask them to make responsible decisions. You know, life is filled with pitfalls. You can't put a [padlock] on life," Brown said, according to the Inquirer. "He's going to have to, like all of us, navigate through NBA worlds and NBA environments with a level of responsibility."
Okafor played 27 minutes and scored 11 points with six rebounds in the 76ers' 116-114 loss to the Houston Rockets on Friday night as Philadelphia moved one loss away from matching the New Jersey Nets' NBA-worst mark of 18 losses to open a season.
The 76ers offered no new comment on Okafor's Thursday morning altercation.
"We've heard some things, but in fairness to everybody here, there's not much more we're going to comment on, at this point," Brown said.
Information from ESPN's Marc Stein and The Associated Press was used in this report.
Sixers supportive of Okafor after street fight
NBA analyst Chris Broussard looks at possible repercussions for Jahlil Okafor after being involved in a street fight in Boston on Wednesday.