This afternoon, D.C. Fire and EMS responded to a mass casualty incident inside the Second Genesis rehabilitation center at 1324 Harvard Street NW. According to FEMS spokesperson Pete Piringer, around 3:15 p.m., emergency responders found a “high level” of carbon monoxide at the facility, as well as several people who had symptoms of carbon monoxide poisoning. Three people were transported from the scene to local hospitals, and Piringer said that “several dozen more” were expected to be transported as a precaution. Hazmat units are still on the scene, and Harvard Street between 13th and 14th Streets NW has been closed to pedestrian and vehicular traffic for the time being.