BEDFORD HILLS, N.Y. (CBSNewYork) — Amid bitter cold, the danger of carbon monoxide poisoning increases with windows shut and the heat cranked up.

As CBS2’s Lou Young reported residents of a Westchester County building ended up sick from carbon monoxide — except for the resident who saved the day.

The three-story, 11-unit apartment house on Babbitt Road in Bedford Hills was turning into a death trap when Angel Flores unexpectedly returned home early from work Sunday night.

Neighbors, and Flores’ own family members, were already getting sick when he went down to the basement and discovered it filling with smoke.

“Thank God I came home and there’s the smell, because half of the people — they would not want to call the fire department or the police because of they’re scared of their status. They’re immigrants, you know?” Flores said.

Flores himself, a U.S. citizen, had no such fear and called 911. Firefighters discovered the oil burner backing fumes into the building.

Flores’ mother was one of five occupants treated for carbon monoxide poisoning.

“She said she cannot breathe, and that she feel, like, pressure in her chest and head. She had a big headache and then heart races,” Flores said.

For the moment, the building has been deemed uninhabitable for building code violations — including a lack of carbon monoxide detectors — which means the guy who called 911 really is a hero.

“If this had been the middle of the night? Yeah, absolutely, there could’ve been some fatalities here,” said Bedford Hills fire Chief Joseph Lombardo.

Residents left with possessions and pets.

“I live in here for 10 years,” said Oscar Morales. “I don’t know what I’m going to do.”

The Bedford Hills building inspector said the building has wiring issues that need to be corrected before people can live there again.

“A lot of these items can be resolved,” said building inspector Alberto Ciraco. “You bring in the licensed electrician, you can get a lot of these taken care of.”

But no one is sure if that can happen during the week before Christmas.

The Red Cross is housing some of the residents without family close by, but all have already been given an incalculable gift for the holiday.

The rent for an apartment in the building runs about $1,200.

The five people who got sick were treated at Northern Westchester Hospital in Mount Kisco. All are expected to recover.