Tokyo (CNN) -- A mammoth earthquake and subsequent tsunami may have caused radioactive material to leak from an atomic power plant in northeast Japan, a major electric company said Saturday, according to a news agency report. Citing the Tokyo Electric Power Co., Japan's Kyodo News Agency said that radioactive substances may have seeped out of the Fukushima Daiichi nuclear reactors, about 160 miles (260 kilometers) north of Tokyo. Meanwhile, potentially dangerous problems cooling radioactive material appear to have cropped up at another of the Tokyo Electric Power Company's nuclear plants. Kyodo reported Saturday that the power company alerted authorities that...