Security precautions taken at White House

Washington (CNN)The first family's departure for Selma, Alabama, on Saturday was delayed after a Secret Service dog detected something suspicious on a vehicle several blocks from the White House, Secret Service spokesman Brian Leary said.

The vehicle in question has been cleared.
The President is scheduled to speak in Selma to commemorate the 50th anniversary of "Bloody Sunday," a watershed moment in the civil rights movement.
Obama, his wife and two daugthers arrived at Joint Base Andrews by motorcade about an hour later than scheduled. The President usually travels by helicopter from the White House to Joint Base Andrews; the Secret Service did not specify to CNN why exactly the first family used the motorcade instead of Marine One, the presidential helicopter.
    Reporters who were gathered to cover the President's departure to Joint Base Andrews were kept inside the White House press room as a security precaution, Leary said.
    The suspicious vehicle was identified on the 1600 block of Constitution Avenue.