Carbon monoxide leak prompts brief evacuation of Philadelphia apartment building

Over two dozen residents at a Philadelphia apartment building were temporarily evacuated Monday night after a reported carbon monoxide leak. 

Emergency first responders were called to the apartment building on Benson Street in the city's Rwanhurst section around 7:30 p.m. for a carbon monoxide alarm.

Authorities say high carbon monoxide levels were detected and 35 people were quickly evacuated. One person was sent to the hospital in unknown condition.

Investigators believe the carbon monoxide leak originated from a water heater. 

Residents were safely allowed back into the building before 9 p.m.