PERTH AMBOY — A carbon monoxide poisoning incident that killed a teenage girl and sickened 35 people has been blamed on a blocked chimney — and a carbon monoxide detector that was not working.

City spokeswoman Noelia Colon said three relatives of the 13-year-old girl killed — a man in his 40s, a 21-year-old woman and a 14-year-old girl — remained hospitalized on Friday following the incident in a three-story apartment building on Fayette Street.

Colon refuted reports that the incident was being investigated as a criminal case.

"It does not look to be suspicious whatsoever," she said. "It looks to be accidental."

An investigation conducted by the police and fire departments, the Middlesex Prosecutor’s Office and Middlesex County Fire Marshal’s Office determined that a clay liner within the building's chimney had collapsed, blocking the exhaust of carbon monoxide. The gas is produced by fuel-burning appliances and engines.

"The building owner indicated that the carbon monoxide and smoke detectors were fully functional in December. However, it was not operational at the time of the incident in the apartment," the city said in a statement released Friday afternoon.

Investigators said a battery had not been properly installed, but it was unclear if this was the fault of the tenant or the building owner.

Apartment in Perth Amboy where dozens were sickened by carbon monoxide (CBS New York)

Authorities have not yet decided whether the building owner, whose family owns several properties in the city, will be fined. Colon said a "comprehensive inspection" will be conducted.

A call left at the building owner's office was not returned Friday.

Colon said that a total of 27 officers were treated for exposure to the odorless, tasteless poison gas. Seven officers were hospitalized for exposure to more concentrated levels.

"They were breaking through doors and windows trying to get some circulation into the building."

Mayor Wilda Diaz offered her condolences to the family of the girl.

"I want to personally thank all of our public safety officials and social service staff for their prompt response. I also want to thank Hackensack Meridian Health Raritan Bay Medical Center of Perth Amboy for their outstanding response to many of the victims. Our hearts go out to all affected. We ask our community to keep everyone involved in prayer for a full recovery,” the mayor said.

The NJ Poison Control Center offered suggestions on reducing the risk of exposure:

  • Only use generators outside. Keep them more than 20 feet from both you and your neighbor’s home, doors, or windows. Carbon monoxide gas can blow back into a building if too close.
  • Clear snow from all heating and dryer vents.
  • Gas appliances must have adequate ventilation. If need be, keep a window slightly cracked to allow airflow.
  • Open flues when fireplaces are in use.
  • Never use the stove to heat your home/apartment.
  • Do not bring generators, pressure washers, grills, camp stoves, or other gasoline, propane, natural gas or charcoal-burning devices inside your home, basement, garage, carport, camper, boat cabin, or tent – or even outside near an open window or door.
  • DO NOT cook with charcoal indoors.
  • DO NOT idle a car in a closed garage. Once you pull in, immediately turn off the engine.
  • Do not idle a car in a snowbank. If stuck in the snow, make sure to clear the tailpipe and surrounding area to prevent exhaust fumes from entering the car.
  • If you do not have any carbon monoxide detectors, install them right away. If your detectors are old and/or not working properly, replace them right away. Check the batteries and replace if needed.

NJ Poison Control Center  said If you suspect Carbon Monoxide poisoning, take immediate action

  • If someone is unconscious or unresponsive, get him or her out of the house and call 9-1-1 immediately
  • Exit the house/building immediately. Do not waste time opening windows. This will delay your escape and cause you to breathe in even more dangerous fumes.
  • Contact your local fire department/energy provider
  • Call the NJ Poison Control Center at 1-800-222-1222 for immediate treatment advice.
  • Do not waste time looking for information on the internet about carbon monoxide poisoning.

Sergio Bichao contributed to this report.

Contact reporter Dan Alexander at Dan.Alexander@townsquaremedia.com or via Twitter @DanAlexanderNJ.