bomb threat

Sheriff Richie Simmons says the courthouse was evacuated and officers began sweeping the building for devices after the threat came in Monday morning.

A North Carolina man who claimed to have a bomb in his truck in front of the Library of Congress gave up after an hours-long standoff with police and is now in custody. No bomb was found in the truck.

The blast comes on the heels of three package-bomb explosions that killed two people and injured two more, as well as a bomb threat that canceled a Saturday concert at the South by Southwest festival.

The threats were allegedly part of the suspect's cyberstalking campaign against a woman with whom he once had a romantic relationship. Juan Thompson once worked as a reporter at The Intercept.

"My instincts tell me this is all part of a coordinated effort," an Ann Arbor police detective tells Michigan Public Radio, discussing threats made in the city.

Twenty-seven Jewish community centers reported receiving bomb threats Wednesday, and 16 received threats Jan. 9. No bombs were found, and the FBI is investigating the source of the threatening calls.