There are basically two types of fires: smoky, smoldering fires that are best detected by alarms with photoelectric sensors and fast fires with flames that are best detected by alarms with ionization sensors.
People are being evacuated after reports of a carbon monoxide issue in Bethel Park.
Firefighters and gas crews scrambled to find the source of a carbon monoxide leak that prompted the evacuation of four businesses in a Greenfield office complex on Tuesday.
An apartment building was evacuated in Rostraver because of carbon monoxide. It happened at building three of the Rostraver Apartment complex on Mathews Road at about 8:30 p.m.
Nine people were taken to the hospital after they were sickened by carbon monoxide. A gas line may have ruptured near a home in the 600-block of Clay Street in Sharpsburg.
People who live in part of an apartment building in Wilmerding are spending Thursday night somewhere else. Ten people were evacuated after a carbon monoxide detector went off.