Lee County Sheriff Jim Johnson said Homeland Security told him several threats were called in at courthouses around the state.
According to the Itawamba County Sheriff Chris Dickinson, everyone got the same notification and the courthouse is evacutated.
Dickinson said it appeared to be a “statewide hoax.”
Other counties reportedly affected include: Clay, DeSoto, Claiborne, Jefferson, Hancock, Harrison, Choctaw, Lowndes, Itawamba, Lee and more.
Greg Flynn with the Mississippi Emergency Management Agency did not have an exact number but said most of the state's 82 counties have been affected and the number was growing Wednesday afternoon.
Flynn said Mississippi's homeland security department and the FBI are investigating.
Anyone with information on the threats was asked to call the homeland security office's Fusion Center at 601-933-7200 or the FBI in Jackson at 601-948-5000.
The Associated Press contributed to this report.