AUBURN CA - Fire investigators were still looking into the cause of a fire that swept through a Penryn house Thursday. The Callison Road house was destroyed by flames but firefighters were able to contain the blaze and keep it from spreading into surrounding trees and brush. Chief Mitch Higgins, of the Penryn Fire Protection District, said Friday that the investigation into the cause was ongoing. Higgins said the building was considered unoccupied at the time of the fire. Its elderly owner no longer lived there, he said. Overnight, the remains of the 900-square-foot, wood-frame building smoldered but firefighters kept the fire in check, Higgins said. During the fire, which was initially reported at about 8 p.m., the Union Pacific westbound track was closed for about two hours.