A man threw fire crackers over the north fence of the White House, hours after a shooting rampage at a Navy Yard here that left at least 13 people dead.
A middle-aged man was arrested near the White House after he threw fire crackers inside its fence, officials said.
Immediately thereafter the press and the White House staff were prevented from leaving the highly guarded complex.
There was an initial sound of firecrackers, which prompted concern from journalists in the area that someone had fired a weapon.
"I heard 2 loud pops coming from outside the fence on the north lawn...Sounded like fireworks. Secret Service tackled a man wearing shorts," twitted Jonathan Karl.
"Secret Service now clearing the entire North Lawn for safety," wrote Ed Henry.
Earlier, at least 13 people, including a gunman, were killed in an audacious mass shooting at the high-security Washington Navy Yard located at a short distance from the White House.
Immediately after the shooting, several buildings in the area were locked down and security was enhanced around the White House, the Pentagon and the US Capitol.
