A man jumped over the White House fence and ran for several seconds towards the executive mansion on Friday, sparking an evacuation within the complex shortly after President Barack Obama and his daughters departed for the weekend.
Journalists and staff were allowed back on to the grounds some time later but a partial lockdown of the northwest side of the building remained in place.
Video showed the intruder running across the White House lawn toward the president's residence.
The U.S. Secret Service has not commented on the incident.
Obama and his daughters had left the White House beforehand, departing on board the Marine One helicopter for Camp David, the presidential retreat in nearby Maryland.
Shortly thereafter, the intruder successfully got on to the grounds, and uniformed Secret Service personnel ordered the press corps and members of the White House staff to evacuate.
No further details were immediately available.
