More than a dozen people at a Brentwood home were sickened Thursday by carbon monoxide poisoning.

Police say the incident occurred around 7 p.m. at a home on Gibson Avenue. Gamaliel Marcano says he was entertaining out-of-town guests when people suddenly felt ill. Marcano says when his young nephew was taken to the hospital, it was determined the sickness was caused by carbon monoxide poisoning.

According to police, 13 people were evacuated from the home.

Fire officials say faulty heating equipment in the basement caused the leak. Authorities originally thought there was an illegal apartment in the home, but that was not the case.

Fire officials also say that propane was being used to run the hot water heater and the gas furnace, instead of natural gas.Authorities say there was a carbon monoxide detector in the basement, but it was not working. News 12 Long Island could not reach the landlord.