A day after a powerful earthquake struck Japan's northwestern coast, officials are investigating the possibility of radioactive leaks at a nuclear power plant. As Catherine Makino reports from Tokyo, the search for people buried under the rubble continues as thousands crowd shelters.

Black smoke rises from a burning electrical transformer near one of Kashiwazaki Kariwa Nuclear Plant's four reactors following a strong earthquake in Kashiwazaki, 16 Jul 2007

However, company officials say neither incident affected the environment.

The water leak was not reported to the public for 12 hours after the quake.

The incident adds to concerns about safety standards at Japan's nuclear power plants, which supply 30 percent of the country's electricity. There have been several accidents and cover-ups in the past few years.

Japanese Prime Minister Shinzo Abe speaks to residents as he visits a temporary evacuation center for quake victims in Kashiwazaki city, 16 Jul 2007

Mr. Abe says the plant was slow to report the fire yesterday. He says he has instructed nuclear plant mangers to report a fire or anything like this as accurately as possible.

Government officials have told Tokyo Electric not to resume operations at the plant until there is a safety review.

Other officials have said the plant's firefighting team did not respond to the blaze as it should have. Four employees tried to fight the fire, but after an hour they gave up and called the fire department for help.

Yuki Kojima of the Kashiwazaki Fire Department questioned the handling of the fire.

He says the fire would have been put out much earlier if the power company had a well-trained firefighting team in place.

At least nine people were killed by Monday's earthquake and nearly 1,000 were injured. More than 13,000 people have crowded into shelters because their homes were damaged or destroyed by the quake, which had a magnitude of 6.8.

Schools and many businesses have been closed and officials do not know when they can reopen. Large areas in Niigata prefecture remain without power or water and telecommunications are down. Airlines are flying emergency supplies to area without charge.