HOUSTON (AP) — Rescuers began a block-by-block search of tens of thousands of Houston homes Thursday, pounding on doors and shouting as they looked for anyone — alive or dead — who might have been left behind in Harvey’s fetid floodwaters, which have now damaged more than 87,000 homes and destroyed nearly 7,000 statewide. Elsewhere, the loss of power at a chemical plant set off explosions that prompted a public health warning, and the city of Beaumont, near the Texas-Louisiana line, lost its public water supply.