At least seven houses in Northwest Washington were evacuated for about two hours Wednesday afternoon after a piece of a rocket-propelled grenade was found in the back yard of a vacant rowhouse, according to D.C. police.

The component was discovered shortly after 2 p.m. in the 5700 block of Third Place NW, in Manor Park, just off Georgia Avenue. D.C. Police Chief Cathy L. Lanier described the component as a piece of a rocket-propelled grenade, or RPG, a shoulder-mounted anti-tank weapon.

Lanier said it is not clear what precisely the component is, but she said authorities are treating it seriously. Police had no information on who found the device or how, or the age of the part.

Authorities removed the device for further investigation about 4:15 p.m. Roads were then reopened and residents were allowed to return to their homes.