White House on Lockdown, Possible Fence Jumper, According to Several Sources

UPDATE: The lockdown due to a fence jumper has been lifted; visitors and staffers are going about their usual activity. 

Multiple news sources are reporting that the White House has been placed on lockdown after an unknown security incident. 

The North Lawn as seen now from inside the White House. We are in lockdown but all seems mostly calm pic.twitter.com/0sU6lQfXjm

— Josh Lederman (@joshledermanAP) April 26, 2016

Secret Service agents were seen clearing the North Lawn and surrounding areas of tourists.