The crew of a nuclear power plant in Japan resorted to flooding the nuclear reactor with sea water to prevent a core meltdown on Saturday after Friday's earthquake.
The earthquake was the most powerful in Japan's recorded history has killed 686 people, though the government says it could likely reach over 1,000, the Associated Press said.
Saturday night, three patients at a hospital tested positive for radiation exposure, in a CNN report.
If the workers fail to cool the nuclear reactor fuel completely, the plant could see enormous damage and radiation could be released into the atmosphere, although experts are saying failure to cool the reactor would be unlikely.
The 8.9 magnitude earthquake caused a tsunami and an explosion at the nuclear plant within a span of 36 hours.