Security officials are searching a vehicle near the White House after firefighters dealt with a fire.
A vendor cart caught fire around 10 am at 15th and G streets, Secret Service spokesman Brian Leary says. Firefighters contained the blaze.
Around the same time, a bomb-sniffing dog detected something on a vehicle at 16th Street and Constitution Avenue. That vehicle is being checked out by the Secret Service and other law enforcement officials.
There is no indication that the two incidents are related.
The fire briefly delayed the departure of President Barack Obama and the first family on Saturday morning. They were heading to Selma, Alabama, for a historic 50th anniversary march.
Reporters at the scene heard a loud noise before they were led back inside.
Nothing dangerous was found and the vehicle was declared safe shortly before noon.