MGN Online

Published: Apr 17, 2013 3:55 PM EDT
Updated: Apr 17, 2013 4:38 PM EDT

BOSTON (AP) - Workers are returning to a Boston federal courthouse that had been evacuated because of a bomb threat amid reports of a breakthrough in the marathon bombings investigation.
    
The U.S. Marshals Service in Washington says the courthouse was evacuated due to a bomb threat. Spokeswoman Nikki Credic-Barrett says authorities conducted a security sweep.
    
Court workers are now going back inside the building, about an hour after the evacuation.
    
Attorney Francis DiMento says he was in a hearing when someone came over the loudspeaker and told everyone to get out.
    
Crowds of reporters are gathered outside. The FBI and the U.S. attorney's office in Boston say no arrests have been made in the marathon bombing.
    
The courthouse has a day care attached and at least one crib was wheeled out.

(Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)