Capitol Police identified the man as 66-year-old Larry R Dawson of Tennessee. He was charged with assault with a deadly weapon and assault on a police officer while armed.
Dawson was taken to a local hospital and underwent surgery. Police said he was in stable but critical condition late on Monday.
Dawson disrupted a House of Representatives session last October by shouting that he was a “Prophet of God”. He was issued a “stay away order” by the District of Columbia Superior Court that same month that required him to avoid the Capitol grounds, court documents show.
The incident, in which a bystander was slightly injured, occurred at the tourists’ entry point to a building that had heightened security even before the terrorist attacks of September 11 2001, and has had periodic scares ever since.
With last week’s suicide attacks in Brussels, Belgium, that killed 35 people fresh on people’s minds, Capitol Police Chief Matthew R Verderosa held a brief news conference at which he preliminarily ruled out terrorism.
“We do believe this is an act of a single person who has frequented the Capitol grounds before and there is no reason to believe that this is anything more than a criminal act,” Mr Verderosa told reporters.
There appeared to be more police officers than usual at some posts outside the buildings as the Capitol and its surrounding buildings resumed business. Even so, the reopening was marred as police investigated a pair of suspicious packages.
By mid-morning, the Capitol Police had cleared one package at the Capitol’s East Front and were investigating another at the Library of Congress Jefferson Building. That resulted in some road closures, and police were not letting additional people into the Capitol Visitor Centre.
Mr Verderosa said he did not know how many officers had fired at the suspect in Monday’s incident. He said no officers were injured.
Mr Verderosa said a weapon had been recovered at the scene and the suspect’s vehicle had been found on the Capitol grounds and would be seized.
He also said a female bystander suffered minor injuries. Later on Monday, spokeswoman Susan Griffiths of George Washington University Hospital said that hospital was about to release a patient it had treated for minor injuries and whom it did not identify.
Bill Miller, a spokesman for the US Attorney’s Office for the District of Columbia, said that after Dawson’s October arrest, he did not appear in court as scheduled the following month. Mr Miller said a bench warrant was issued for his arrest and in January. Dawson wrote the court a letter in which he claimed to be exempt from laws because he is a prophet of God.
“No longer will I let myself be governed by flesh and blood, but only by the Divine Love of God,” he wrote, adding four exclamation points.
Other court paperwork said Dawson said he was previously in the Army and was honourably discharged in 1971.