The White House was locked down this afternoon, CBS reports. 

The incident began after the Secret Service reported a car tried to follow a motorcade through the security checkpoint at 17th Street and Pennsylvania Avenue.

The vehicle was stopped by uniformed Secret Service officers and the driver was placed under arrest. CBS reports the driver was a U.S. Treasury Department pass holder. 

The motorcade was for the Obama daughters. The suspect remains in custody.

The vehicle was swept now by the the Metropolitan Police Department.

Correspondent Knoller says the Secret Service hasn't revealed who was in the motorcade but President Obama never left the White House.