Tokyo (CNN) -- Japanese authorities rushed Friday to cool down fears as well as radioactive temperatures inside a nuclear power plant rattled by Friday's mammoth earthquake, with the nation's prime minister planning a trip to personally inspect the atomic facility.

The Fukushima Daiichi nuclear reactor, located about 160 miles north of Tokyo, "remains at a high temperature" because it "cannot cool down," Chief Cabinet Secretary Yukio Edano told reporters.

Trade Minister Banri Kaieda said that a small radiation leak could occur at the plant, Japan's Kyodo News Agency reported early Saturday morning.

These and other issues caused by the 8.9-magnitude tremor prompted authorities to order an evacuation of people within 2 to 3 kilometers (1.2 to 1.8 miles) of the plant, a move Edano called "precautionary." Those farther away -- within 3 to 10 kilometers -- were asked to stay in their homes. The Kyodo news agency estimated the evacuation order directly affected about 3,000 people.
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That decision notwithstanding, Japanese Prime Minister Naoto Kan plans to head to the region. He will set off by helicopter around 6 a.m. Saturday to personally inspect the plant, according to Edano.

Earlier Friday, U.S. President Barack Obama said that Kan told him there had been no evidence so far of radiation leaks from nuclear reactors because of the earthquake and tsunami.

The Fukushima plant and three others were shut down after the quake, as Japan declared a state of atomic power emergency.

Cham Dallas, a professor of disaster management at the University of Georgia, said that it wouldn't be surprising if reactors get "both thermally hot and radioactively hot" after the reactors were shut down.

"When they shut down reactors, it takes a long time for them to go down," Dallas said. "It does not necessarily mean radioactive material got out of the reactor."

While authorities are "bracing for the scenario," the minister said, "At this moment, there is no danger to the environment."

Fire broke out at a second facility, the Onagawa plant, but crews put it out, according to the International Atomic Energy Agency.

The trouble at the Fukushima plant happened after the plant successfully shut down, Edano said. Crews had difficulty generating enough electricity to pump water into the facility to cool it, he said.

Janie Eudy told CNN that her husband, Joe, was working at the plant and was injured by falling and shattering glass when the quake struck. As he and others were planning to evacuate, at their managers' orders, tsunami waves struck and washed buildings from the nearby town past the plant.

"To me, it sounded like hell on earth," she said, adding that her husband ultimately escaped.

The government said earlier that it was sending senior officials and the defense force's Chemical Corps to the Fukushima power plant, according to the Kyodo News Agency.

The International Atomic Energy Agency said Friday on its website that its officials are "in full response mode," as they worked with Japanese authorities and monitor the situation.

Using Air Force planes, the U.S. government has sent over coolant for the Fukushima plant, Secretary of State Hillary Clinton said Friday.

"We're really deeply involved in trying to do as much as we can on behalf of the Japanese and on behalf of U.S. citizens," she said.

James Acton, a physicist who examined Japan's Kashiwazaki nuclear plant after a 2007 earthquake, told CNN that Japanese authorities are in race to cool down the Fukushima reactor.

"If they can't restore power to the plant (and cool the reactor), then there's the possibility of some sort of core meltdown," he said.