MOUNT VERNON — The Skagit County Fairgrounds office building was reduced to rubble Tuesday morning, weeks after it was declared structurally unsound.

The building was vacated earlier this month after structural problems became apparent during a March 6 meeting. About 65 people had gathered in an upstairs conference room when a county employee felt the building shake. The crowd was evacuated, and no one was hurt. But the building was permanently closed.

Skagit County commissioners later called for the decades-old structure to be demolished.

The building apparently received a poorly constructed addition decades ago. Joists that made up the then-single-story building’s roof were transformed into floor supports, and beams for the new roof were not properly supported, according to former county facility management director Roger Howard. Howard, who now does consulting work for the county, was at the site Tuesday watching as the building was torn down.

The county now plans to assess all buildings on the fairgrounds. Meanwhile, staff from the fairgrounds office have moved into temporary work trailers as they await a decision on a permanent replacement.

Fair Manager Leslie Collings said Tuesday that no long-term decision has been made and that the staff will work in the temporary units at least through the end of the fair and possibly longer.

Deputy County Administrator Tim Hollaran said the county is still studying its options but expects a decision soon.