John A. Gotti, the former boss of the Gambino crime family, was stabbed in the stomach over the weekend in Syosset, N.Y., the authorities said on Monday.

The circumstances of the stabbing remain unclear, and a law enforcement official who spoke on the condition of anonymity said Mr. Gotti, 49, was not cooperating with investigators.

Shams Tarek, a spokesman for the Nassau County district attorney, said, “I can confirm for you that the district attorney’s office is investigating, in conjunction with the Nassau County Police Department, an alleged stabbing of John (Junior) Gotti in Syosset on Sunday.”

The stabbing is believed to have occurred in a CVS pharmacy parking lot, the law enforcement official said. But the authorities learned of the stabbing only when a Long Island hospital called the police to report that a patient had arrived with a stab wound, the official said.