A second hydrogen explosion rocked a crippled Japanese nuclear reactor Monday, spewing a giant cloud of smoke into the air and injuring 11 workers, officials said.
The blast was so large it could be felt 25 miles away.
The plant's operator, however, insisted that radiation levels around the facility remained within legal limits.
A similar explosion was triggered Saturday at the Fukushima Dai-ichi reactor after cooling systems were damaged by Friday's earthquake and tsunami.
Officials said a separate damaged reactor at the facility was also experiencing severe problems after its fuel rods became fully exposed, raising the risk of overheating and yet another explosion.
A state of emergency has been declared at six reactors where cooling systems and backup generators failed following Friday's twin disasters.
More than 180,000 people have been evacuated from areas around the plant and 160 were reported to have suffered radiation exposure.
U.S. officials said 17 American military personnel involved in helicopter rescue missions were exposed to low levels of radiation.
Meanwhile, a tide of bodies washed up along the coast of Miyagi Prefecture, one of the hardest hit by the towering tsunami wave.
The official death toll has risen to 10,000, but is expected to climb.
Officials in one town said they were running out of body bags.
"We have requested funeral homes across the nation to send us many body bags and coffins. But we simply don't have enough," said Hajime Sato, an official in Iwate Prefecture, which was also heavily hit.
In the city of Soma, the crematorium was unable to handle the crush of bodies being brought for funerals.
"We have already begun cremations, but we can only handle 18 a day. We are overwhelmed and are asking other cities to help us deal with bodies," said Katsuhiko Abe.
Millions of survivors were forced to cope without water, food or heating in near freezing temperatures, as rescue crews struggled with the scope of the disaster.
"People are surviving on little food and water. Things are simply not coming," said Sato.
Aftershocks continued to rock the country, with a 6.2-magnitude quake Monday triggering a second tsunami scare.
"I'm giving up hope," said Hajime Watanabe, a 38-year-old construction worker lining up for
gasoline in Sendai. "I had a good life before. Now we have nothing. No gas, no electricity, no water."
The Japanese stock market plunged a dramatic 6% Monday, its first day opening since the disaster, on the likelihood of huge losses at Japanese industrial giants.