A blaze Friday at the old Bellamy Telephone building, in the 1400 block of Jackson Street in Knoxville is being investigated. Knoxville Fire and Rescue Chief Jim Mitchell says the cause is undetermined at this time; some minor combustibles burned at the site. He says the building is empty, there was minimal damage and the blaze was extinguished by the time fire crews arrived. He says there was some heavy smoke damage, but nothing about it was suspicious.