Cause Revealed in Deadly NY Mall Carbon Monoxide Leak

Similar tragedies are all too common during the winter months.

Feb. 24, 2014— -- A faulty water heater flue pipe caused the carbon monoxide leak that killed a New York restaurant manager and sent more than two dozen people to hospitals, a fire official said.

Huntington Chief Fire Marshal Terence McNally said Sunday the fumes were circulated in the basement by the ventilation systems at the Legal Sea Foods restaurant at the Walt Whitman Shops on Long Island.

Authorities initially went to the restaurant after receiving a call about a woman who had fallen and hit her head in the basement. But when first responders arrived, they started feeling sick, too – and suspecting a carbon monoxide leak, evacuated the restaurant and two other nearby businesses.

Evelyn Toloza was one of the employees rushed out of the mall.

“They were just trying to get everybody out as fast as they could,” she said.

After the restaurant was evacuated, 27 people were treated at hospitals. During the evacuation, police found a man unconscious in the basement. Restaurant manager Steven Nelson – a father of two – was pronounced dead at a hospital.

Roger Berkowitz, president and CEO of Legal Sea Foods, said Nelson, 55, had worked for the restaurant for three years.

"It's a shock, he was a great guy, we consider ourselves a family," Berkowitz said. “He sort of epitomized the family spirit that we have.”

Berkowitz said the carbon monoxide leak was "a wakeup call for commercial businesses" and that monitors should be in all businesses.

Tragedies of this nature are all too common during the winter months. A day after the Long Island incident, a similar scare was reported at a Maine hotel, with seven people hospitalized after showing poisoning symptoms.

An average of 430 people die each year from accidental carbon monoxide poisoning and more than 15,000 are hospitalized. While carbon monoxide is odorless and colorless, its effects are quickly felt – including headaches, nausea and dizziness.

ABC News senior medical contributor Dr. Jennifer Ashton says getting away quickly is key.

“The treatment for people who suspect or know they have carbon monoxide poisoning include immediately removing themselves from that environment, getting into fresh, open air, and if necessary, seeking immediate medical attention,” Ashton said.

Despite incidents like the two this weekend, only 25 states require carbon monoxide detectors in certain residential buildings. Most states, including New York, do not require them in restaurants or malls.

Police said a coroner would officially determine Nelson's cause of death. Autopsy information was not immediately available Sunday.

No problems had been found when the restaurant was inspected last March, and another inspection was scheduled for next month, McNally said.

ABC News Radio and The Associated Press contributed to this report.