For the second time in three days, the White House has been put on lockdown because of a security breach.
The Secret Service says two people threw something over the fence surrounding the White House complex - one person from the south side and one from the north.
The two have been detained and questioned.
The incident follows an hour-long lockdown Tuesday after a vehicle followed a motorcade bringing President Barack Obama's daughters home through the gates.
The driver was charged with unlawful entry, a misdemeanor.