PHOTOS: Powerful images reveal Harvey's destruction, first reponders' humanity

HOUSTON (AP/KRIV) - Houston's fire department prepared Thursday to begin a block-by-block search of thousands of flooded homes in a city wrecked by Harvey, as the official death toll from the storm climbed to at least 31.

The city's assistant fire chief, Richard Mann, said his department would ensure "no people were left behind." Farther east, Beaumont and Port Arthur struggled with rising water after being pounded with what remained of the weakening storm.

Meanwhile, fires and two explosions rocked a chemical plant northeast of Houston early Thursday. Fire authorities said the blasts at the Arkema Inc. plant were small and that while some deputies suffered irritated eyes from the smoke, the materials that caught fire shortly after midnight are not toxic.

The plant lost power after the storm, leaving it without refrigeration for chemicals that become volatile as temperatures rise. Arkema had shut down the plant before Harvey made landfall.

The photos above — taken by various branches of the Defense Department, along with the Department of Homeland Security — capture some of the damage wrought by Harvey thus far, as well as on-the-ground rescues being carried out by authorities.