Just before 5 am, Caldwell fire crews were called to a blaze just off Simplot Blvd. A second alarm was called in immediately. Caldwell fire officials say the building near the warehouses was once a gymnasium owned by the Crookum Company, no one was inside at the time of the fire. A third alarm was called in with crews from Star and Eagle coming to assist the Caldwell and Nampa fire departments. An investigation is underway.