Neighbors became aware of the tragedy as firefighters and other investigators went door to door, checking carbon monoxide levels on the block.
Firefighters were called to the building on East 172nd Street when the first alarm went off at around 3 a.m. and turned off the boiler, but three hours later, carbon monoxide filled the building.
Mayor Bloomberg signed legislation today relating to the notification and reporting of the possible presence of PCBs in city schools. The presence of toxic PCBs in schools has been a hot button issue for parents for a long time.
Residents on Baldwin Avenue in Jersey City are on edge after two people, and possibly a third, died on the same day they moved in.
Officials said three neighbors were also affected by the gas leak. All had nonlife-threatening injuries.
A Nissan Altima nearly became a death trap on Thursday afternoon. Two children were hospitalized, one in critical condition, after being overcome by carbon monoxide gas in the Bronx.
The fire department says a faulty feeder overheated in the subbasement Friday morning. That created a smoky condition that elevated levels of the gas.
Six Sleepy Hollow residents ended up in the emergency room Sunday night after someone in a home brought a lit charcoal grill into the house to barbecue.