MIYAKO, Japan - Amateur video shows tsunami waves rushing through cities in northeast Japan on Friday.
Tsunami waves in Miyako City barreled through a narrow bay and sent ships crashing into highway overpasses.
The water carried houses, cars and debris inland. People were seen standing on rooftops as the water swirled around their homes.
Countless homes were reduced to rubble.
The earthquake that spawned the tsunami was the world's fifth most powerful in the past century.
On Sunday, temperatures began to sink toward freezing in northeastern Japan, compounding the misery for survivors coping without water, electricity or proper food in the region battered by the tsunami.
Japan's prime minister says the country is facing its most severe challenge since World War II. Officials say at least 1,400 people were killed. But the police chief of Miyagi state says the death toll there alone could pass 10,000.
Japanese troops today rescued a survivor about 10 miles offshore. The tsunami had swept the 60-year-old man out to sea as he clung to the roof of his home. The man told his rescuers that he and his wife were trying to gather their belongings when the tsunami hit. She was swept away.
Meanwhile, Tokyo Electric Power says it will ration electricity with rolling blackouts in parts of Tokyo and other cities. The planned blackouts of about three hours each will start tomorrow. They are meant to help make up for a severe shortfall after key nuclear plants were left inoperable due to the earthquake and tsunami in northeastern Japan.
The U.N. nuclear agency says Japan has declared a state of emergency at another earthquake-affected nuclear plant where higher-than-permitted levels of radioactivity were measured.
The International Atomic Energy Agency says Japan informed it that the source of the radioactivity at the Onagawa power plant is being investigated. It said all three reactors at the plant are under control.
Japan also said authorities at another plant have resorted to using sea water to cool a second reactor in an attempt to prevent a meltdown. Japan said earlier attempts to cool the No. 3 reactor at the Fukushima Dai-ichi plant had failed. Sea water is corrosive and is being used as a last resort.
Meanwhile, a Japanese utility report that one of two pumps in the cooling system at a third nuclear plant has failed. Japan Atomic Power says the reactor is operating normally on the one pump, and there's no risk of a radiation leak.