The victim was reportedly coming to the aid of a friend when he was stabbed in the stomach.
Dormer was rushed to Stony Brook University Medical Center with a non-life threatening injury.
Police say he was not involved in the original fight.
One person was taken into custody and charges are pending.
The victim was identified as the adult son of Suffolk County Police Commissioner Richard Dormer.
Richard Dormer joined the department in 1963, retired as chief in 1993 and returned as commissioner in 2004.
[GET EYEWITNESS NEWS DELIVERED: Click here to sign up]
MORE NEW YORK AND TRI-STATE AREA NEWS
USEFUL LINKS:
SEND TIP OR PHOTO || REPORT TYPO || GET WIDGET
EYEWITNESS TWITTER || FIND US ON FACEBOOK
