The Washington fire department reported a fire at a food cart near the White House and that its units had extinguished it.
It was unclear if the fire was the source of the noise.
“As pool and other press gathered outside near the South Lawn for the departure of President Obama and he First Family on the way to Selma, Ala., for a historic 50th anniversary march, a loud noise was heard,” the report by David McCumber of the Hearst Newspapers, said.
“The Secret Service then moved press back into the briefing room and locked the doors,” the pool report said. -AFP