New York (CNN) -- A restaurant manager died and one of his employees remained hospitalized after inhaling carbon monoxide at a Long Island mall, authorities said Sunday.
Another 26 people were treated and released after the incident, according to hospitals.
Police and emergency crews rushed to Walt Whitman Shops in Huntington Station, New York, on Saturday night after reports that a woman had collapsed in the basement of Legal Sea Foods. Once they arrived, they felt dizzy as well and determined that the cause was carbon monoxide poisoning, said police in Suffolk County, New York.
"Police evacuated the restaurant and found the manager, Steven Nelson, 55, of Copiague, unconscious in the basement," a statement said. "He was transported to Huntington Hospital where he was pronounced dead."
A sign on the restaurant's door now says the building has been condemned as being unsafe and unfit for human habitation.
Investigators found a leak in the flue pipe of the water heater, said A.J. Carter, a spokesman for the town of Huntington.
Authorities sent the restaurant a summons for faulty equipment, which carries a fine of up to $2,000, Carter said.
Colorless, odorless carbon monoxide is produced by the incomplete combustion of fossil fuels like oil and natural gas.
The restaurant didn't have a carbon monoxide detector. State fire codes require them only in establishments where people sleep, Carter said.
Legal Sea Foods is subject to annual inspection, and there were no issues when a town official inspected the restaurant in March. The restaurant was scheduled for another inspection at the end of next month.
The restaurant and surrounding businesses were evacuated as a precaution Saturday, but authorities said the carbon monoxide appeared limited to the basement of the restaurant.
National Grid shut off a gas line shared by Panera Bread and Legal Sea Foods as a precaution, Carter said.
Before either restaurant can reopen, he said, they'll have to get plumbers to check for leaks and receive certification from the town's plumbing inspector.
Boston-based Legal Sea Foods offered its condolences to Nelson's relatives.
"We are devastated by the news of carbon monoxide poisoning at Walt Whitman Mall and the death of our General Manager Steve Nelson. Our thoughts and prayers are with Steve's family and all those who were affected by the leak," the restaurant said in a statement posted on its website. "Steve's tragic death is a shock to all of us at Legal Sea Foods. He was one of the finest people we've ever had the pleasure of working with. We are deeply saddened. Our restaurant remains closed."