Eight courthouses in Washington reported bomb threats late Thursday afternoon. The courthouses were in Thurston, Chelan, Columbia, Benton, Adams, Douglas, Pacific and Clark counties.
Four courthouses were declared "all clear" by 5:30 p.m. Police continue to check the others.
Officials said a man called the Thurston County Clerk's Office and said multiple explosive devices had been planted on the property.
Authorities said they are now trying to locate the person responsible.