Former Spc. Paul Michael Murray served as an unmanned aerial vehicle operator from March 2010 to April 2014, Army spokesman Gabriel Ramirez said in a statement.
Police found an AR-15 style rifle, 113 rounds of ammunition and five 30-round magazines in Murray's car, which was parked about a block away, according to a CBS story detailing the police report.
Vice President Kamala Harris and her husband have not moved in yet because of renovations to the home in Northwest D.C., near the U.S. Naval Observatory.
Murray was seen on Massachusetts Avenue and detained by Secret Service officers stationed near the residence. Police charged Murray, of San Antonio, Texas, with carrying a large-capacity ammunition-feeding device, a dangerous weapon, a rifle and unregistered ammunition.
CBS News reported that Murray "had been experiencing paranoid delusions of the government and military being after him."
Police said Murray's mother received a text from him Wednesday morning saying "he was in Washington and would be taking care of his problem," CBS reported.
On March 10, police in Texas issued a bulletin about Murray that said he had told authorities he had been medically discharged from the Army for schizophrenia and that he owned an AR-15, according to Task & Purpose.
Ramirez would not confirm the reasons behind Murray's discharge because of privacy concerns.
Murray had no combat deployments during his time in the Army, Ramirez said in the statement.
Murray's awards and decorations include the Army Good Conduct Medal, National Defense Service Medal, Global War on Terrorism Service Medal, Non-Commissioned Officer Professional Development Ribbon, Army Service Ribbon and Aviation Badge.
-- Matthew Cox can be reached at firstname.lastname@example.org.