According to the ministry, a total of 11 nuclear reactors were automatically shut down at the Onagawa plant, Fukushima No. 1 and No. 2 plants and Tokai No. 2 plant after the biggest-magnitude quake in the country's modern history.

The Fukushima prefectural government advised some 2,000 residents in a radius of 2 kilometers of the No. 2 reactor of the Fukushima No. 1 plant to evacuate, government officials said. The officials said the operator, Tokyo Electric Power Co., reported the level of water going down in the reactor.

Tokyo Electric also said the system to cool reactor cores in case of emergency stopped at the No. 1 and No. 2 reactors of its Fukushima No. 1 nuclear plant.

At the Onagawa plant in Miyagi Prefecture, a fire started at a building housing the turbine, the operator, Tohoku Electric Power Co., said, denying it detected any signs of radiation leaks. Water spilled from pools containing fuel rods at the Kashiwazaki-Kariwa plant on the Sea of Japan coast in Niigata Prefecture and the Onagawa plant.

Hokkaido Electric Power Co. reported no problems at its Tomari No. 1, No. 2 and No. 3 plants on the northernmost main island.

There were no immediate signs of any problems at the Hamaoka nuclear plant on the Pacific coast in Shizuoka Prefecture, southwest of Tokyo, the prefectural government said.