Jersey City, NJ – Residents of a two-story, nine-unit complex on Tonnelle Avenue were forced into the cold early this morning after high levels of carbon monoxide were detected in the building, Jersey City officials said today.

Firefighters and EMS crews responded to 157 Tonnelle Ave. off Van Winkle Avenue at 12:41 a.m. after carbon monoxide detectors went off in the building, Fire Director Armando Roman said.

Roman said all residents in the building’s nine units had to be evacuated due to the high carbon monoxide levels. Roman could not estimate how many people live in the building.

PSE&G workers were notified of the incident and shut off the gas feed to the complex, Roman said. Roman added that the source of the high levels is believed to be a blocked flue pipe.

Roman said that despite the high levels, there were no injuries and residents were allowed to return to their homes shortly before before 3 a.m.

Carbon monoxide, a colorless, odorless gas, is created by fuel burning appliances, such as a hot water heater, stove, or generators, Roman said. In most cases, Roman said that high levels of carbon monoxide can occur when any of those appliances are improperly ventilated.