Philadelphia, PA – A carbon-monoxide detector is being credited with saving lives overnight at a home in Philadelphia’s Manayunk section.

Officials said firefighters received a call about 2 a.m. for a carbon-monoxide alarm. When firefighters arrived to the house, on Baker Street near Dupont, they detected heavy CO readings inside, officials said.

The people who were inside the house at the time all made it out safely. Authorities said the CO leak was caused by a malfunctioning heater and credited the house’s CO detector and alarm with saving residents’ lives.

A house next door was also affected by the fumes, officials said, but no one was home at the time.