The Harford County Circuit Courthouse on Bel Air's Main Street received an unspecified bomb threat Thursday morning that the sheriff's office said proved to be unfounded.A call came in to one of the judge's chambers at about 8:25 a.m. from a male voice and mentioned explosives in the courthouse, Lt. James Eyler of the sheriff's office said Thursday afternoon."The threat was not specific. It did not list a date or a time," Eyler said. "They determined it was a non-credible threat because it was not specific."Sheriff's deputies searched the courthouse, but did not evacuate the building. Everyone did, however, end up leaving the building for a reason unrelated to the bomb threat."While they were searching, they located a faulty smoke detector and the smoke detector went off and the building was evacuated," Eyler said.Eyler said the courthouse does occasionally get bomb threats, "especially on a specific trial date because they [defendants] don't want to go to trial."Thursday's threat, he added, "was pretty much uneventful."