Fire officials are trying to determine what set a storage unit ablaze over the weekend. Firefighters were dispatched to a report of a storage unit on fire at 1200 Main Street South shortly before 10 a.m. Saturday. After quickly extinguishing the fire, crews spent about two hours overhauling, according to a post on the Southbury Fire Department’s Facebook page. The fire happened on the former Romatic Manufacturing Company property. The Southbury Fire Marshal’s office is investigating the cause.