The prime minister said it was the nation's worst crisis since World War II. (AP Photo/Koji Sasahara) (Associated Press) 
 
 Buildings are covered with mud in Rikuzentakata, Iwate Prefecture, northern Japan, Saturday, March 12, 2011, after a powerful tsunami created by one of the strongest earthquakes ever recorded swept through... (Associated Press) 
 
 A stranded elderly woman is carried on the back of a Japanese soldier after being rescued from a residence at Kesennuma, northeastern Japan, on Saturday March 12, 2011, one day after a giant earthquake... (Associated Press) 
 
 A ship washed away by tsunami sits amid debris in Kesennuma, Miyagi prefecture, Sunday, March 13, 2011 after Japan's biggest recorded earthquake hit its eastern coast Friday. When spotted,... (Associated Press) 
 
 Nuclear plant operators worked frantically to try to keep temperatures down in several reactors crippled by the earthquake and tsunami, wrecking at least two by dumping sea water into them in last-ditch efforts to avoid meltdowns. Residents said the water surged in and quickly rose higher than the first floor of buildings.
– When officials decided to vent radioactive steam from one of the damaged nuclear power plants in Japan, they knew it could result in a hydrogen explosion. And, even though an explosion is exactly what happened, the decision was still the best option for avoiding a total meltdown, the AP reports in an interesting piece that traces the chain of events from Friday, when the earthquake damaged the Fukushima Dai-ichi nuclear complex, to this morning, when a total of six reactors were placed under a state of emergency. More from Japan: The estimated death toll is more than 10,000 as of today, with the prime minister calling this disaster Japan’s worst crisis since World War II, the AP reports. The confirmed dead number more than 1,800. Nuclear plant operators dumped sea water into two reactors in a last-ditch attempt to keep temperatures down, as officials warned a second explosion could occur, but would not pose a health threat. Experts confirm to Reuters that “this is not a serious public health issue at the moment,” and that the winds will likely carry contamination to the Pacific, where it will not threaten any other nations. The next crisis facing Japan could be an economic one, Reuters reports. Automakers, electronics firms, and oil refineries have been forced to suspend operations at some of their factories, and many companies are not sure how soon they will be back up and running. Even so, experts say the economy could bounce back in months. Click for more on Japan.