D.C. Fire and EMS  responded to a report of a “strange white powder” in the Letterman House, located at 2030 F St., Sunday night, blocking off  a portion of F Street in the process.

Captain Donald Martin said officers received a report of suspicious powder in a personal residence inside the building. Martin said D.C. Fire always treats calls of this nature as dangerous until the substance is tested.

The powder was determined to be harmless at about 7:45 p.m.

D.C. Fire spokesman Pete Piringer said residents of the room where the powder was located had left town for a few days and returned to find the dust-like white powder in their apartment.

Piringer said field tests determined the powder may have been associated with drywall bits from nearby construction that might have entered the room through the ventilation system.

Residents were not evacuated from the Letterman House but those already inside the building were advised to shelter in place.