A California man, who had a bayonet and machete with him, was arrested near Democratic National Committee headquarters in Washington, authorities said Monday.
Donald Craighead, a 44-year-old resident of Oceanside, was booked on suspicion of possession of prohibited weapons, U.S. Capitol Police said.
Craighead's Dodge Dakota pickup truck, decorated with a swastika and other white supremacist symbols, was spotted near DNC headquarters at around midnight, authorities said.
The truck did not have a license plate, but instead had the picture of an American flag where the plate should have been, officials said.
Capitol police pulled over the truck along the 500 block of South Capitol Street, SW.
"This is good police work plain and simple," Capitol Police Chief Tom Manger said in a statement. "We applaud the officers' keen observation and the teamwork that resulted in this arrest."
Officers spotted the bayonet and machete, which are illegal in Washington D.C., inside the truck, authorities said.
Craighead allegedly told police he was "on patrol" and expressed white supremacist ideology.
It was not immediately clear on Monday if Craighead had hired, or been assigned, an attorney yet.
Craighead's brother and father in California told NBC News that the suspect has been estranged from his family for years and loved ones didn't know where he had been living.
Years ago, the suspect was diagnosed with schizophrenia and had responded well to medication before he stopped taking them, according to his father, also named Donald Craighead.
"He's (now) a homeless drifter who calls me when needs money for food," the concerned father said. "No, he's not well."
A DNC representative could not be immediately reached for comment on Monday.