TACOMA – U.S. Marshalls conducted a three-day sex offender sweep in Washington state, resulting in 12 arrests.

The News Tribune reported Friday that the sweep, called Operation Evergreen, aimed at arresting people who failed to register as sex offenders, some of whom fled to other states.

Authorities say one man was found hiding under a pile of debris in a warehouse. They say another man was found hiding in a house thanks an anonymous tip.

The Pacific Northwest Violent Offender Task Force, which includes local, state and federal officers, has arrested more than 13,978 sex offenders since it was created in 2010.