A plumber working on basement pipes in a Kingston apartment building on Second Brook Street accidentally set the residence ablaze with the torch he was using, starting a fire that spread to the floors and walls, ultimately displacing six families, fire officials said. The two-alarm blaze started just after 3 p.m. Sunday, and required the assistance of nearly a half-dozen surrounding communities, said Kingston Fire Captain Stephen Heath. The fire began on the basement walls and traveled up to the first floor, where it burned between two apartments, causing about $100,000 in damage, Heath said. No one was injured. American Red Cross representatives said their organization was helping the displaced families find temporary housing.