The New York Daily News, which was the first to report the incident, said a law enforcement source said the younger Gotti was knifed in the stomach Sunday night while trying to stop two strangers from fighting in the parking lot of a CVS drug store in Syosset on Long Island.
The source said the 49-year-old Gotti walked into Syosset Hospital to get treated for his wound and he was transferred to North Shore University Hospital.
The Daily News said an operator at the hospital said Monday afternoon there was no patient with Gotti's name there. WNBC-TV, New York, reported, however, Gotti was in stable condition.
Gotti's attorney, Charles Carnesi, said he was unaware of the incident.
The Daily News' source said the Nassau County Police Department and Nassau County District Attorney's Office were investigating. WNBC-TV said no arrests had been made in the 9:30 p.m. attack.
Gotti has said he quit the mob in 1999 when he pleaded guilty to racketeering charges that sent him to prison for six years, and Carnesi said Gotti now manages properties he owns on Long Island.
Gotti was reputed to have led the Gambino crime family for much of the 1990s while his father was in prison, where he died in 2002.