According to Newsday, a North Shore University Hospital spokeswoman said the eight were treated and released, and returned to the Kings Point school Monday morning.
The conditions of the other students, who were taken to other hospitals, were not immediately known.
Authorities said a water heater was found to be leaking carbon monoxide shortly before 10 p.m. Sunday. The leak was in the Academy's Barry Hall.
The Merchant Marine Academy prepares students for careers in the maritime industry. Its 82-acre campus is on Long Island, about 20 miles east of New York City.