Inundated rivers have posed the latest threat from persistent storms that have killed at least 23 people since last week as they doused the region with heavy rain and spawned destructive tornadoes.

Rescuers in an increasingly bleak search picked through the tornado-splintered ruins of Kentucky homes and businesses Sunday, including a candle factory that was bustling with night-shift employees when it was flattened, as the governor warned that the state’s death toll from the outbreak could top 100.