Now Playing:Aerial video Japan's mega-quake near nuclear plant center
Description: Japanese Prime Minister Naota Kan is telling people living near a crippled nuclear power plant to stay indoors. Kan went on NHK Television in Japan today to warn people of the dangers of being exposed to elevated radiation levels. He says radiation has spread from four reactors of the Fukushima Dai-ichi nuclear plant in northeastern Japan following Friday's 9.0 magnitude earthquake and tsunami. And, he says, there's a threat of further leaks of radioactive substances. Some 70000 people living within 12 miles of the nuclear plant already have been evacuated. But another 140000 remain in the new warning zone of within 19 miles of the plant. The prime minister says engineers are working hard to prevent any further radioactive leaks or explosions.