The U.S. Secret Service has heightened security efforts after a motorist drove a car up to a White House checkpoint late Saturday and claimed to have a bomb.
A Secret Service spokesman said a criminal investigation has been launched.
It was not immediately clear whether there was a bomb in the car.
Two incidents Saturday
President Donald Trump was not in the White House. He is spending the weekend at his Mar-a-Lago resort in Florida, his fifth weekend there since taking office January 20.
The incident happened just hours after the Secret Service apprehended a person who jumped over a bicycle rack outside the security perimeter of the White House.
Reports say Secret Service officers tackled the intruder and arrested him within two minutes.
Alarm bells at the White House went off after the security breach attempt, prompting dozens of long-gun-armed officers to run out on the lawn to prevent it.
On March 10, a California man climbed over three White House security barriers and managed to remain free on the grounds for more than 15 minutes before he was detained near a door to the White House. Trump was in the White House at the time.