A 7.2-magnitude earthquake centered in the northern state of Iwate about 250 miles northeast of Tokyo, rocked a rural, mountainous area of northern Japan, killed at least three people and injured more than 100 on Saturday, TV channels reported.

One of the people killed was caught in a landslide, Chief Cabinet Secretary Nobutaka Machimura told reporters. A second man was hit by a car after running out of a building and a third was killed by falling rocks at a dam construction site.

Seven people were trapped in a hot-spring resort inn hit by a landslide but police had rescued five and were trying to get the other two out, NHK public TV reported.

The earthquake triggered landslides, stopped train service and knocked down a bridge. With roads closed, military aircraft and helicopters were mobilized to assess the damage.

The quake was centered in the northern state of Iwate about 250 miles northeast of Tokyo, and was located about five miles underground. It was felt as far away as Tokyo.

The earthquake, which measured 7.2 on the Richter scale, also caused a leak of radioactive water from a power plant, although the company said that the amount was so small that there was no cause for public concern, AFP reported.

There was no danger of tsunami, but several aftershocks, including one with a magnitude of 5.6, struck the area in the hours after the initial quake. The quake has been followed by some 153 aftershocks.

Electricity had been cut to about 29,000 households in the quake zone. Its force has buckled countless roads, including one highway severed when a stretch of land collapsed, creating a cliffside.

Earthquakes are common in Japan, one of the world's most seismically active areas. The country accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater, prompting tough building codes to try to limit damage.