Washington's Union Station was evacuated for a brief period at the height of the evening rush on Wednesday over a suspicious package, officials said.
Commuters swarmed through its classic front archways into the searing summer heat. Packs gathered on its expansive plaza and in grassy areas across the street, just blocks from the Capitol.
K-9 units assisted police scouring the part of the terminal serving Amtrak passengers. Union Station is also a hub for commuter rail, subway and city and long-distance bus service.
The evacuation was ordered after D.C. firefighters were tending to a medical emergency and asked for help in dealing with an unspecified threat. Transit police tweeted that they were investigating a suspicious package.
Metro Transit Police gave the all clear after 20 minutes and normal operations resumed.