A construction worker was killed and two others were injured when their attempt to waterproof a basement and install a Jewish ritual bath caused an explosion strong enough to blow out a wall in a home, the fire department said. Witnesses described a furious blast that shook nearby homes, knocked out windows and covered the Brooklyn neighborhood in smoke. They said at least one victim stumbled out of the house naked and on fire. The workers were using a type of epoxy sealant that is flammable and is not for indoor projects, fire department Deputy Chief Michael Quinn said. When one of the workers turned on a power tool, it caused the explosion, which blew out a wall on the first floor of the house and buckled another wall. City officials said the homeowners did not have a permit to install the bath. The victims' names were not immediately released. The two who survived the explosion, which occurred around 11:30 a.m., were hospitalized with burns on about 85 percent of their bodies. The third was declared dead at the scene.