Officers were told around 5 a.m. to be on the lookout for a man with a gun, U.S. Capitol Police spokeswoman Sgt. Kimberly Schneider said.
Officers then saw the man, who pointed the gun at them at 2nd and C streets in southwest Washington near the Capitol, the U.S. Botanic Garden and the National Museum of the American Indian. Officers opened fire after the man refused to drop his weapon because they were in "fear for their lives," Schneider said.
Senate Sergeant at Arms Terrance Gainer, who is responsible for maintaining security in the Capitol, said in a statement that the man had a loaded, semiautomatic handgun and had parked his car near where he was shot.
The man, whose name has not been released, was brought to a hospital. His condition was not immediately known. It was also unclear how many shots were fired.
D.C. police were assisting with the investigation.