At least 42 people were taken from the United States Merchant Marine Academy in Kings Point to area hospitals for evaluation late Sunday night after carbon monoxide was discovered leaking from a water heater at the facility, Nassau County and Kings Point police said.
The leak came from a water heater in the basement of Barry Hall, said Sgt. James Dalgish of the Kings Point Police Department.
Barry Hall is located in the middle of the campus.
The entire building was evacuation as a precaution, Dalgish said.
It was not known when people would be allowed back in to the facility.
Authorities said no one lost consciousness during the leak, but three of those transported were listed in serious condition at a hospital.
Three people at the scene refused to be transported for treatment, authorities said.
A report of a "positive rating" for carbon monoxide came in shortly before 10 p.m., a Nassau police spokesman said.
Fire and emergency medical service vehicles were on the scene as well as a police helicopter, a Nassau police spokeswoman said.