It could have been a whole lot worse.

But no one was hurt after a carbon monoxide (CO) scare at apartments in East Brainerd in Chattanooga Tuesday night, according to the Chattanooga Fire Department (CFD).

A release says a resident at the Meridian at Hamilton Place Apartments called CFD to have their CO levels checked, because their CO detector was sounding the alarm.

That alarm was right: Firefighters found elevated CO levels in the residence, and they evacuated everyone inside.

They also determined a nearby apartment had elevated levels, so a resident and their pet were also evacuated.

Firefighters worked quickly to find the source, checking the gas fireplace, flue, dryer, and other appliances, as well as sources outside the building.

While this was going on, more residents were evacuated.

It turns out work had been done on the gas heat system on the roof earlier in the day.

The gas company put locks on all of the meters for apartments that had any level of reported CO.

No one was hurt.

Thanks to the concerned citizen who notified the fire department and potentially stopped a dangerous situation from becoming much worse,' a CFD release says. 'Their carbon monoxide alarm was their first sign that something wasn’t right.'

Many homes have smoke detectors, but does yours also have a CO detector? CFD recommends you fix that right away if you don't.