Japanese authorities struggled to contain new nuclear emergencies on Tuesday — including a possible rupture in a reactor containment vessel — as the death toll continued to climb with search teams reaching towns that were flattened by last week’s earthquake and tsunami.
The National Police Agency said Tuesday afternoon that 2,722 people have died, and many thousands were still missing. Bodies continued to wash ashore at various spots along the coast after having been pulled out to sea by the tsunami’s retreat.
Some 400,000 people were living in makeshift shelters or evacuation centers, officials said. Bitterly cold and windy weather that was pushing into northern Japan was compounding the misery as the region struggled with shortages of food, fuel and water.
An explosion Tuesday morning at the Fukushima Daiichi Nuclear Station — the third reactor blast in four days — damaged the vessel containing the nuclear core at reactor No. 2 , government officials said, and there was a growing fear of a catastrophic meltdown.
The overwhelmed operator of the nuclear plants, Tokyo Electric Power Company, confirmed there had been radiation leaks and that water was being pumped into three overheated reactors in the Fukushima complex.
A fire that broke out Tuesday morning at a fourth reactor was extinguished by mid-afternoon, although the government’s chief spokesman, Yukio Edano, later said that temperatures were now rising inside a fifth and sixth reactor in the complex.
People living within about 12 miles of the reactors at Fukushima were ordered to evacuate, and those within about 20 miles were told to stay indoors and close all windows, doors and vents. If people had laundry hanging outside, the government advised, they should not bring it inside or touch it.
Tokyo-area residents began to buy and stockpile food, water, candles and batteries as shelves at grocery stores became increasingly bare. Prime Minister Naoto Kan went on national television to implore people not to panic.
But there was plenty of panic in the stock market: Fevered selling drove down the Nikkei stock index by 10.6 percent at the close of trading.
There were scattered news reports of some foreigners fleeing Japan, and one Western diplomat said Tuesday night that “anecdotes and rumors” were swirling in the international community.
Still, there appeared to be no mass exodus. The United States Embassy, for example, was not urging resident Americans to leave.
The ambassador, John V. Roos, said that about 1,300 Americans were living in the five northern prefectures most affected by the earthquake and the tsunami. American consular officers were making their way to Sendai and other northern cities on Tuesday to conduct “welfare-and-whereabouts” checks on American citizens there.
“We are encouraging U.S. citizens to heed the instructions of the Japanese civil defense authorities,” Mr. Roos said.
The commander of American forces in Japan, Lt. Gen. Burton M. Field, confirmed that some American troops aboard three helicopters had been contaminated by radiation when they apparently flew through a radioactive plume released from the crippled nuclear complex.
“We found contamination on the clothes of several crew members, and one crew member had some on his skin,” said General Field. “The exposure rate was about the same as you would get over a monthlong period outside in the sun. We assess that as very, very low.”
He added that the crew members got a good scrubbing with soap and water and were back on duty.
Chinese health and environmental officials on Tuesday gathered for emergency meetings on how to respond in case radioactive fallout hit China. The government said it was stepping up monitoring for radiation and would swiftly report results.
China’s Meteorological Administration said prevailing winds would carry radioactive material away from China until Thursday, and possibly beyond. “China will not be affected,” the agency said on its Web site.
Air China canceled all flights to and from Tokyo and Sendai until Thursday.
Nations such as South Korea and Singapore have announced they would bolster inspections of Japanese food imports.
The United States Geological Survey revised the magnitude of the earthquake to 9.0, from 8.9, but it was the subsequent tsunami that did the most damage. The initial wave scoured away entire communities, and desperate survivors searched Tuesday for signs of friends and relatives who remained missing.
There was plenty that was missing in the fishing village of Minamisanriku: the city hall, the hospital, the shipyard, police stations — and 8,000 people.
The tsunami might have crashed most heavily into this town that once was home to more than 17,000. Situated at the back of a mountainous V-shaped cove, the town was swamped by the first surge of muck and seawater that was 30 feet high as it roared between the valley walls.
As the deluge pressed in on them, Sanae Sato, 71, said 400 townspeople rushed to the community center where she worked. They thought the five-story building would be high enough to protect them. But when the water reached the fourth floor, they all sought shelter in the attic.
From the attic window, Ms. Sato said, she saw the floodwaters hurling cars along, with drivers and passengers still inside. Houses broke from their foundations and were carried along, their owners perched on the ridges of the roofs.
“I saw people trying to balance on the rooftops like surfers,” she said. “It didn’t work. It was like hell.”
The Miyagi prefectural government said Tuesday that search teams had located 2,000 people in Minamisanriku who had been missing and presumed dead. They had fled to surrounding towns as the tsunami bashed the coastal areas of the town.
Troopers from Japan’s Self-Defense Forces cleared roadways into the village on Tuesday as a long line of fire trucks waited to enter. Closer to shore, teams of searchers rummaged through the crushed houses and collapsed shops. They peered into cars that had been swallowed by the mud, hoping to find survivors. Searched cars were marked with yellow tape.
One gruesome discovery was a mud-caked woman hanging by her head from the roof of a gas station. She was brought down, covered in a blue plastic tarp, and her body was laid by the station to await collection by another disaster team.
Rescue teams from 13 countries pressed on with the searches in other towns, some assisted by dogs. In the air, helicopters shuttled back and forth, part of a mobilization of some 100,000 troops, the largest since World War II.
Because Fukushima have been lost to the national power grid, Tokyo Electric announced plans for rolling blackouts across the region to conserve electricity — the first controlled power cutbacks in Japan in 60 years.
The first set of blackouts Tuesday morning began in four prefectures outside Tokyo. The utility, which provides service to 45 million people in the region, said the cuts could continue for six weeks.
Public conservation of electricity was significant enough, the company said, that the more drastic blackout scenarios were being scaled back. Still, anticipating deep and lengthy power cuts, many people were stocking up on candles, water, instant noodles and batteries for radios.