Kashiwazaki, Japan ? The mayor ordered that a nuclear power plant hit by a strong earthquake be shut down today until its safety could be confirmed after a long list of problems – including radiation leaks, burst pipes and fires – came to light.

Kashiwazaki-Kariwa is the world’s largest nuclear plant in power output capacity. Signs of problems after Monday’s quake came first not from the officials, but in a plume of smoke that rose up when the quake triggered a small fire at an electrical transformer.

It was announced only 12 hours later that the magnitude 6.8 temblor also caused a leak of about 315 gallons of water containing radioactive material. Officials said the water leak was well within safety standards. The water was flushed into the sea.

Later Tuesday, it said 50 cases of “malfunctioning and trouble” had been found. Four of the plant’s seven reactors were running at the time of the quake, and they were all shut down automatically by a safety mechanism.

Hiroshi Aida, mayor of Kashiwazaki, a town near the epicenter that is home to the plant and 93,500 people, ordered operations halted Wednesday for “safety reasons.”

“I am worried,” he said. “It would be difficult to restart operations at this time. … The safety of the plant must be assured before it is reopened.”

Plant operator Tokyo Electric Power Co. said the quake was stronger than planned for at its seven-reactor Kashiwazaki-Kariwa plant. But none of the problems posed serious threats to people or the environment, it said.

Tsunehisa Katsumata, president of Tokyo Electric Power Co., toured the site today, declaring it “a mess.”

“We will conduct an investigation from the ground up,” Katsumata said. “But I think fundamentally we have confirmed that our safety measures worked.”

Across town, more than 8,000 residents hunkered down for their second night in shelters. The death toll – nine, with one person missing – was not expected to rise significantly. Most of the newer parts of town escaped major damage.