NAKAMINATO, Japan — Japan on Saturday mobilized a nationwide rescue effort to pluck survivors from collapsed buildings and rush food and water to thousands in an earthquake and tsunami zone under siege, without water, electricity, heat or telephone service.

Entire villages in parts of Japan’s northern Pacific Coast have vanished under a wall of water, many communities are cut off, and a nuclear emergency was unfolding near two stricken reactors at one plant as the country tried to absorb the scale of the destruction after Friday’s powerful earthquake and devastating tsunami.

Japanese news media estimates of the death toll ranged from 1,300 to 1,700, the total could rise. Many communities were scrambling to find the missing; in the port town of Minamisanriku, nearly 10,000 people were unaccounted for, according to the public broadcaster NHK.

Much of the northeast was impassable, and by late Saturday rescuers had not arrived in the worst-hit areas. More than 300,000 people have been evacuated, including tens of thousands fleeing the zone around the nuclear plants in Fukushima prefecture even before news that problems at one plant appeared to be escalating quickly.

Most of the deaths were from drowning, but Japan’s Self-Defense Forces and firefighters were rushing to prevent a higher toll, rushing up the coast in helicopters and struggling to put out fires burning in industrial complexes or sweeping through Japan’s many vulnerable wooden homes.

Japan had clearly learned the lessons of the devastating Kobe earthquake of 1995, when Japan refused to accept offers of international help early enough, leading to criticisms that many of the 6,000 deaths could have been avoided.

The United States, which has several military bases in Japan, is sending in helicopters, destroyers, and an aircraft carrier, the Ronald Reagan, which has the ability to act as a hospital as well as to convert sea water into drinking water, said a spokesman for the Navy’s 7th Fleet in Japan.

Severe aftershocks continued to rock a traumatized country. The U.S. Geological Survey recorded 90 earthquakes off the eastern coast on Saturday alone, five of them with magnitudes larger than 6.0. Kyodo News reported more than 125 aftershocks since Friday afternoon’s earthquake.

The continual swaying and rolling of the ground deepened the disorientation of a nation accustomed to disaster — earthquakes, tsunamis and two atomic bombs — but which has not experienced anything on this scale for generations.

Aerial photographs of the ravaged coastal areas showed a string of cities and villages leveled by the power of the tsunami. Plumes of black smoke rose from burning industrial plants. Stranded ships bobbed in the water. Town after town reported that parts of their population were unaccounted for. Survivors gathered on rooftops, frantically shouting or signaling for help.

With phone service cut throughout the area, some radio and television stations broadcast pleas from people trying desperately to find their family members or at least to assure them that they were alive. “This is Kimura Ayako in Sapporo, looking for the Tanakas in Soma,” one caller said. “We are OK Please tell us your location.”

JR, the railway company, reported that three passenger trains had not been accounted for as of Saturday night, amid fears that they were swept away by the tsunami. There were reports of as many as 3,400 buildings destroyed and 200 fires raging. Analysts estimated that total insured losses from the quake could hit $15 billion, Reuters reported.

Mobilizing the troops

Even as estimates of the death toll from Friday’s quake rose, Japan’s prime minister, Naoto Kan, said 50,000 troops would be mobilized for the increasingly desperate rescue recovery effort. Meanwhile, several ships from the U.S. Navy joined the rapidly-expanding rescue effort. The USS McCampbell and the USS Curtis Wilbur, both destroyers, prepared to move into position off Miyagi prefecture.

In addition, the Ronald Reagan Carrier Strike Group was expected to arrive today. Besides serving as a hospital, it can also be used as a platform for refueling helicopters from the Japanese Self Defense Forces working more closely to shore.

Convoys of Japanese military helicopters could be seen flying over the earthquake zone Saturday, and trucks filled with soldiers were moving heavy equipment into the area.

Igor Sechin, Russia’s deputy prime minister, said the Japanese authorities were requesting additional energy supplies, and that Russia may increase deliveries of coal and liquefied natural gas to northern Japan.

While aftershocks from the earthquake continued, the tsunami wreaked the most damage. Tsunami experts estimated that despite Japan’s extensive warning systems and drills, there would only have been between 15 and 30 minutes after the earthquake struck before the tsunami washed in, leaving those in coastal areas precious little time to flee.

One-third of Kesennuma, a city of 74,000, was reported submerged, the BBC reported, and photographs showed fires continued to rage there. Iwate, a coastal city of 23,000 people, was reported nearly destroyed, the BBC said.

Local television here reported that the authorities had found 300 to 400 bodies in the town of Rikuzentakata, in Iwate prefecture. In Minamisoma, in Fukushima prefecture, 97 residents of a retirement home were found dead. And an additional 100 bodies were found Saturday in Miyagi prefecture, near the quake’s epicenter, bringing the total in those places to more than 500.

Military units were in Sendai on Saturday, working at evacuation shelters or helping search-and-rescue teams. Sendai’s website, posted in Tokyo because much of the north was still without electricity, recorded a grim list of the toll: 1.4 million homes in the city without electricity, and 500,000 homes without water.

“The rescue is going on through the night, of course,” Michael Tonge, a teacher from Britain, said early this morning from his home in Sendai. “I think people want to help, but the government is telling them not to, as the professionals are better equipped to do that.”

Japan’s rising death toll is anyone’s guess

As Japan entered its second night since the magnitude-8.9 quake, there were grim signs that the death toll could soar. One report said no one could find four whole trains. Others said 9,500 people in one coastal town were unaccounted for and that at least 200 bodies had washed ashore elsewhere. The government said 642 people were missing and 1,426 injured. Atsushi Ito, an official in Miyagi prefecture, among the worst-hit states, could not confirm the figures, noting that with so little access to the area, thousands of people in scores of towns could not yet be reached. “Our estimates based on reported cases alone suggest that more than 1,000 people have lost their lives in the disaster,” Edano said. “Unfortunately, the actual damage could far exceed that number considering the difficulty assessing the full extent of damage.”