The United States Capitol in Washington (AP Photo)
A man flying a mini helicopter illegally landed his aircraft on the west lawn of the US Capitol Wednesday, triggering street closures around the building and prompting a police investigation.
"The US Capitol Police continues to investigate, with one person detained," USCP officer Shennell Antrobus told AFP.
The arrested pilot, according to the Tampa Bay Times who had interviewed and filmed him prior to his audacious flight, is a Florida man who was conducting an act of civil disobedience - in this case a demand for campaign finance reform.
Air space is severely restricted around Washington landmarks including the White House and the Capitol, which houses the US Congress whose 535 lawmakers were in session at the time. The incident was in apparent violation of the prohibitive flight zone.
Police said a bomb squad was dispatched to inspect the gyrocopter, which landed a few hundred yards (meters) from the Capitol.
Authorities reportedly put the building on temporary lockdown although it was not evacuated. Iraq's Prime Minister Haider al-Abadi was scheduled to be in the Capitol meeting with senators.
Witness Rachel Jackman expressed alarm about the surprise incident. "Within minutes, the entire area was shut down. I mean, there were probably 30 or 40 of the Capitol police there, cars, some black SUVs as well," she told CNN.
The breech, during a high-volume tourist season, was the latest in a series of recent security scares in Washington.
On Saturday, a man holding a protest sign shot and killed himself near the steps of the US Capitol, triggering a brief lockdown and police reports of a man "neutralized" after a shooting.
In January, a man who turned out to be an intelligence agency employee lost control of a hobby drone and crashed it into the White House gardens, sparking a US Secret Service investigation.
And last September, a knife-wielding Iraq war veteran jumped the protective White House fence and ran into the mansion before he was apprehended.
The Times identified Wednesday's pilot as Dough Hughes, 61.
"I'm demanding reform and declaring a voter's rebellion in a manner consistent with Jefferson's description of rights in the Declaration of Independence," Hughes reportedly wrote in letters to all 535 members of Congress and which he carried with him on his flight.
Hughes is described as a mailman, and a logo appearing to be that of the US Postal Service was visible on the tail fin of the aircraft.
Photographs tweeted by Times reporters showed the gyrocopter flying over the National Mall before landing.
The paper also reported it asked the Secret Service if it was aware of Hughes' plan, and that officers there said they were not and referred a reporter to Capitol Police.
A USCP sergeant told the Times that Hughes "hasn't notified anybody" of his planned flight.