No one else was reported to be hurt in the shooting.
Trump has been briefed on the incident, according to White House deputy press secretary Hogan Gidley.
The police department will take the lead on the investigation. Law enforcement authorities have identified the victim but are withholding the man's name pending notification of his family, the spokesperson said.
The White House was placed on lockdown and the surrounding area cordoned off by emergency personnel Saturday after an apparent gunshot was heard. Trump is expected to return to Washington D.C. this evening to attend the Gridiron Dinner. On February 23, a woman was arrested after crashing her vehicle into a security barrier near the presidential residence.