At least six people were taken to the hospital after they were exposed to high levels of carbon monoxide while operating propane-powered equipment inside a Gaithersburg, Maryland, building.
The workers were operating the equipment inside a building at 15200 Omega Drive Saturday morning, Montgomery County Fire and Rescue Service spokesman Pete Piringer said on Twitter.
Piringer said the area were the workers were lacked ventilation, and the carbon monoxide reading was at 200 ppm. At 200 ppm, a person can start to experience "dizziness, nausea, fatigue and headaches after two to three hours of exposure," according to detectcarbonmonoxide.com.
The building was evacuated, and nine workers were evaluated. At least six of them were taken to the hospital with non-life-threatening injuries.
No one else was inside the building.