WASHINGTON - POLICE have evacuated the massive Capitol Visitor Center after finding a suspicious package at its entrance.

Capitol Police say they are investigating whether the package is dangerous.

About an hour after the evacuation began in late afternoon on Monday, fire trucks, ambulances and others that responded to the evacuation began leaving the area.

The underground visitor centre opened in December. At 53,880 sq m, it is three-quarters the size of the Capitol itself.

Nearly 3 million people visit the complex each year. It is not uncommon for tourists to leave belongings behind accidentally, but security at the Capitol is tight. -- AP