A small fire broke out Saturday evening in an attic at the Russell Senate Office building on Constitution Avenue near the Capitol. (courtesy of United States Senate Historical Office)

A man was seriously injured in an apartment fire in the Mount Pleasant area Saturday. Later in the day, a separate fire broke out in the Russell Senate Office Building on Capitol Hill.

The Mount Pleasant fire, in the 1600 block of Park Road NW, was caused by flammable materials stored too close to a heat source, according to the D.C. fire department. The fire in the Russell building apparently broke out around three motors in an attic, said fire department spokesman Vito Maggiolo. He said sprinklers extinguished it.

Air-handling equipment apparently wafted a haze of smoke through parts of the building at 2 Constitution Avenue NE, he said. It was the haze and the smell of smoke that sent firefighters to the building about 6 p.m. Saturday, Maggiolo said.