According to CNN (only on broadcast, no web link yet), the lockdown at the White House took place after someone tried to jump over the White House fence. That person was taken into custody.
Previous reports seemed to indicate that the White House lockdown was due to the U.S. Capitol shooting and lockdown. However, is has since been reported that it was due to the separate incident of an attempted fence jumping at the presidential residence.
The annual 2016 White House Easter Egg Roll is taking place today, and Beyonce and Jay Z were surprise guests, along with their daughter Blue Ivy.
Previous White House Security Breaches
In October 2014, a man jumped the fence onto the North Lawn and was jumped on by security dogs before being detained. In September of that year, a man was able to enter the White House and run through most of the main floor before being detained. Also that September, someone scaled the fence before being detained. In August 2014, a toddler squeezed through the fence. In March 2014, a suspect was arrested for climbing the fence.
In June 2013, a man crashed a driverless jeep into a gate on Pennsylvania Avenue as a diversion in an attempt to spray paint the side of the White House.
In 2011, a gunman was arrested in Pennsylvania in connection with shootings near the White House that included shots that were stopped by bulletproof glass in White House windows.
In 2009, a woman wearing a backpack jumped the White House fence. Also in 2009, Michaele and Tareq Salahi famously crashed a state dinner for the Indian Prime Minister at the White House.
See a complete list of White House security breaches.