Authorities are searching for clues after a rash of bomb threats were called into courthouses in 28 Oregon locations Monday.Between 2:30 and 4 p.m. on Monday, officials say threats were called into the courthouses and the Oregon Public Service building in Salem. All of the threats came in by telephone -- most to the main switchboard lines at each of the facilities. Officials say 22 of the 28 buildings were evacuated, but according to the latest reports, no actual evidence of explosives was found. These calls came in just four days after eight courthouses in Washington State received such threats, including in Benton County.

The FBI has been called in to assist in the investigation. The calls did not come directly to the courts, but were relayed through employees or offices. Officials have now turned to the public asking for tips even anonymously.

Officials won't say if the Washington and Oregon incidents are connected. A number of Nebraska courthouses had similar experiences Nov. 2.

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