UPDATE: Breaking news from CNNs twitter that authorities pumping seawater into plant to cool it. And health workers are distributing iodine -- given to counter radiation exposure-- to people in the plants vicinity.

WAKI, Japan (AP) — An explosion at a nuclear power station Saturday destroyed a building housing the reactor, but a radiation leak was decreasing despite fears of a meltdown from damage caused by a powerful earthquake and tsunami, officials said.
 Government spokesman Yukio Edano said the explosion destroyed the exterior walls of the building where the reactor is placed, but not the actual metal housing enveloping the reactor. The Skanner News Video
 That was welcome news for a country suffering from Friday's double disaster that pulverized the northeastern coast, leaving at least 574 people dead by official count.The scale of destruction was not yet known, but there were grim signs that the death toll could soar. One report said four whole trains had disappeared Friday and still not been located. Local media reports said at least 1,300 people may have been killed.

Edano said the radiation around the Fukushima Dai-ichi plant had not risen after the blast, but had in fact decreased. He did not say why that was so. The pressure in the reactor was also decreasing after the blast, he said.

The explosion was preceded by puff of white smoke that gathered intensity until it became a huge cloud enveloping the entire facility, located in Fukushima, 20 miles (30 kilometers) from Iwaki. After the explosion, the walls of the building crumbled, leaving only a skeletal metal frame.



Tokyo Power Electric Co., the utility that runs the Fukushima Dai-ichi plant, said four workers suffered fractures and bruises and were being treated at a hospital.

"We have confirmed that the walls of this building were what exploded, and it was not the reactor's container that exploded," said Edano.

The trouble began at the plant's Unit 1 after the massive 8.9-magnitude earthquake and the tsunami it spawned knocked out power there, depriving it of its cooling system.

The concerns about a radiation leak at the nuclear power plant overshadowed the massive tragedy laid out along a 1,300-mile (2,100-kilometer) stretch of the coastline where scores of villages, towns and cities were battered by the tsunami, packing 23-feet (7-meter) high waves.

It swept inland about six miles (10 kilometers) in some areas, swallowing boats, homes, cars, trees and everything else.

"The tsunami was unbelievably fast," said Koichi Takairin, a 34-year-old truck driver who was inside his sturdy four-ton rig when the wave hit the port town of Sendai.

"Smaller cars were being swept around me," he said. "All I could do was sit in my truck."

His rig ruined, he joined the steady flow of survivors who walked along the road away from the sea and back into the city on Saturday.

Smashed cars and small airplanes were jumbled up against buildings near the local airport, several miles (kilometers) from the shore. Felled trees and wooden debris lay everywhere as rescue workers coasted on boats through murky waters around flooded structures, nosing their way through a sea of debris.

According to official figures, 586 people are missing and 1,105 injured. In addition, police said between 200 and 300 bodies were found along the coast in Sendai, the biggest city in the area near the quake's epicenter.

The true scale of the destruction was still not known more than 24 hours after the quake since washed-out roads and shut airports have hindered access to the area. An untold number of bodies were believed to be buried in the rubble and debris.

Meanwhile, the first wave of military rescuers began arriving by boats and helicopters.