Mysterious White House blast came from suspicious vehicle

A suspicious vehicle spotted by a Secret Service dog some blocks from the White House on the 1600 block of Constitution Ave. triggered a security alert and lockdown at the presidential residence Saturday.
The Secret Service spokesman said later that the situation was contained and there was no threat. He did not answer questions about the cause of the loud blast, a small ball of fire and the large plumes of black smoke seen around the White House. Because of the incident, President Obama and family were held up more than a hour in departing for Selma, Alabama for a speech on the 50th anniversary of “Bloody Sunday,” and instead of traveling by the helicopter waiting on the South Lawn, the first family traveled by motorcade to Joint Base Andrews. The reporters gathered at the White House to cover their departure were meanwhile locked inside the White House Press room as a security precaution.