Suffolk County police identified the man who died as Steven Nelson, a manager at the Legal Sea Foods restaurant at the Walt Whitman Shops in Huntington Station on Long Island. The restaurant is located in a detached building that is part of the mall, which remained open.
Police said 27 others affected by carbon monoxide were taken to area hospitals. WABC-TV reported that all but a handful of patients had been treated and released.
Four ambulance personnel and three officers were among those overcome by carbon monoxide at the complex, which is about 35 miles east of New York City, police said. They responded to a call shortly after 6 p.m.
Police Lt. Jack Fitzpatrick said the initial call was about a woman who had fallen in the basement of the Legal Sea Foods outlet.
He said that when rescue workers arrived at the scene they started to feel lightheaded and nauseated and suspected a carbon monoxide leak.
The woman who fell was taken to Huntington Hospital, as was Nelson, who was pronounced dead there. There was no immediate word on the woman's condition.
Fitzpatrick said all of those affected by the fumes were restaurant employees, police or ambulance workers. He said the leak appeared to originate with the heating system.
"Right now, we are inspecting the heating system, and this incident seems to be confined to the basement area. It does not appear to have made it in the area of the restaurant where the customers were," he said.
Carbon monoxide is odorless and colorless and can lead to death by suffocation.
The Legal Sea Foods restaurant, a Panera and a Cheesecake Factory outlet were evacuated as a precaution.
"They told us to leave because of a gas leak," Cheesecake Factory patron Kathy Sella said. "I didn't want to blow up or anything like that. We were at the bar having a glass of wine and then one of the waitresses she said you have to leave."
The Walt Whitman Shops consists of more than 80 stores, including anchors Bloomingdale's, Lord & Taylor, Macy's and Saks Fifth Avenue.