WRC-TV in Washington reported that the fire broke out at Frager's Hardware about 6 p.m. Wednesday. Crews arrived to find flames bursting through the roof.
The fire on Pennsylvania Avenue, about 11 blocks south of the U.S. Capitol, sent dark smoke drifting over the Capitol dome and Nationals Park, where the Nationals were hosting the Mets.
Two firefighters suffered minor injuries.
John Weintraub, one of the owners of Frager's, tells WJLA-TV that the fire started in a lumber area on the side of the store.
D.C. Councilmember Tommy Wells called the hardware store, established more than 90 years ago, "a DC landmark and an absolute gem to the Capitol Hill community."