Parts of Union Station in the nation's capital were evacuated late Wednesday afternoon due to a bomb threat. The evacuation took place for less than 20 minutes, before the all clear sounded. 

Metro Transit Police said that it was investigating a suspicious package near the Amtrak portion of the station. Police used a K-9 unit to assist in the investigation. 

The police also said that a number of entrances into the station were closed as police investigated the suspicious package.