Smoke rises from a stricken reactor at the Fukushima Daiichi Nuclear Power Station in Japan.

The estimated death toll from Japan's crippling earthquake and tsunami was revised to more than 10,000 today as officials worked to prevent a nuclear disaster.

"The earthquake, tsunami and the nuclear incident have been the biggest crisis Japan has encountered in the 65 years since the end of World War II," Prime Minister Naoto Kan told a news conference today. "We're under scrutiny on whether we, the Japanese people, can overcome this crisis."

Some 200 bodies were recovered today, and the official death toll from the earthquake and subsequent tsunami stood at 1,217 as of Sunday evening, Japanese police told The Chosunilbo, but that number is expected to climb to between 20,000 and 30,000. In one town alone, only 15,000 out of 75,000 were able to evacuate' the rest remain missing.

Hoping to prevent a nuclear meltdown at the Fukushima Daiichi nuclear power plant, officials began venting the containment of reactor unit 3 through a controlled release of vapor intended to lower pressure inside the reactor structure, the International Atomic Energy Agency reported. Residents near the plant some 170 miles northeast of Tokyo evacuated the area after a quake-triggered power outage left a cooling system unable to supply water to cool the reactor. The original 2-mile evacuation radius has expanded to 12.5 miles and involves some 210,000 residents.

The earthquake, which today was upgraded to a 9.0 magnitude from 8.9, left almost 2 million households without power in the freezing north and about 1.4 million without running water, the government said.

Meanwhile, the benchmark Nikkei 225 stock average dropped 494 points, or 4.8 percent, to 9,760.45 as the market opened Monday--the first business day after the twin disasters. The Bank of Japan said Monday it would inject 7 trillion yen ($86 billion) into the financial system to help stabilize the market.