White House on lockdown amid alert
The White House is on lockdown for the second time in three days because of a security breach, officials have said.
The Secret Service said two people threw something over the fence surrounding the complex in Washington - one person from the south side and one from the north.
The pair were being detained for questioning.
Secret Service officers were ordering people in the West Wing to stay inside.
The incident follows an hour-long lockdown on Tuesday after a vehicle followed a motorcade bringing President Barack Obama's daughters home through the gates.
The driver was charged with unlawful entry.