Shocking stories of deaths emerge as the military is enlisted to help at the Fukushima Daiichi nuclear plant

The devastating impact of the Japanese earthquake on the country's ageing population was exposed on Thursday as dozens of elderly people were confirmed dead in hospitals and residential homes as heating fuel and medicine ran out.

In one particularly shocking incident, Japan's self-defence force discovered 128 elderly people abandoned by medical staff at a hospital six miles from the stricken Fukushima nuclear plant. Most of them were comatose and 14 died shortly afterwards. Eleven others were reported dead at a retirement home in Kesennuma because of freezing temperatures, six days after 47 of their fellow residents were killed in the tsunami. The surviving residents of the retirement home in Kesennuma were described by its owner, Morimitsu Inawashida, as "alone and under high stress". He said fuel for their kerosene heaters was running out.

Almost a quarter of Japan's population are 65 or over, and hypothermia, dehydration and respiratory diseases are taking hold among the elderly in shelters, many of whom lost their medication when the wave struck, according to Eric Ouannes, general director of Doctors Without Borders' Japan affiliate.

This comes after Japan's elderly people bore the brunt of the initial impact of the quake and tsunami, with many of them unable to flee to higher ground.

Although the people from the hospital near Fukushima were moved by the self-defence forces to a gymnasium in Iwaki, there were reports that conditions were not much better there. An official for the government said it felt "helpless and very sorry for them". "The condition at the gymnasium was horrible," said Cheui Inamura. "No running water, no medicine and very, very little food. We simply did not have means to provide good care."

Japan's deepening humanitarian crisis came as the military was enlisted to try to douse the damaged nuclear reactors and spent fuel pools at the Fukushima plant using helicopters and high-powered hoses. Chinook helicopters dropped several tonnes of water, much of which seemed to miss its target. More workers were drafted into the danger zone to prevent the spread of radiation and the plant's operator said it had managed to connect an electric cable to allow it to restart critical water pumps in one of the six units.

The US Nuclear Regulatory Commission chairman, Gregory Jaczko, said the commission believed "radiation levels are extremely high" at the plant, while Britain said citizens should not go any closer than 50 miles from the plant, much further than Japan's recommendation to stay 12 miles away or take shelter indoors if evacuation was not possible within an 18-mile radius.

Sir John Beddington, Britain's chief scientific adviser, also said he believed cooling water essential to preventing radioactive emissions from the spent fuel pools alongside reactor 4 had almost totally evaporated and he was "extremely worried" the storage pools at reactors 5 and 6 were also leaking.

The Japanese government revised the estimated disaster death toll up from 10,000 to 15,000. It confirmed that 5,178 people had died and 2,285 were injured. The number of missing was increased to 8,913 from 7,844. Almost 200,000 households regained electricity, but this left more than 450,000 without power. Approximately 2.5m households still do not have access to water.

Pat Fuller, of the International Federation of Red Cross and Red Crescent Societies, which met on Thursday in the earthquake zone to plan longer term relief with the Red Cross of Japan, said the lack of heating oil was critical.

"They don't have enough kerosene to run heaters for all the evacuation centres," he said. "Only a small percentage of the petrol stations are functioning which affects efforts to get food back into the shops. There had been an outbreak of gastric flu at one health centre we visited and if that hits old people there could be serious complications."

Search and rescue teams began scaling back their operations as relatives began to lose hope of finding missing loved ones alive. In the town of Kamaishi, American and British teams completed their final sweeps, and Japanese mechanical diggers began the task of clearing collapsed homes, offices and stores.

Crews found more than a dozen bodies, some trapped beneath homes flipped on their roofs, another at the wheel of his overturned car. In three days of searching the battered coast, they found no survivors. "We have no more tasks," said Pete Stevenson, a firefighter heading Britain's 70-strong team. "The Japanese government have told us they are now moving from search and rescue to the recovery phase."

Heather Heath, a British firefighter, said: "There are probably dozens of bodies we just can't reach. The water can force people under floorboards and into gaps we can't search. It's such a powerful force."

In Rikuzentakata Katsuya Maiya, whose home was hit by the tsunami, said he had accepted he would not find his 71-year old sister-in-law and her husband. The elderly couple fled their home on foot, but they could not keep up with their neighbours and fell behind as the tsunami rushed in.

"I think there is no hope," he said. "The only thing that I can do is wait until members of the Japanese self-defence force collect their bodies."

The very young too were suffering. Save the Children on Thursday reached Ishinomaki, Nobiru and Onagawa, north of Sendai, and reported children living in miserable conditions. "There were some terrible scenes, in some places like Onagawa there was nothing left," said Ian Woolverton, who led the mission. "In other places like Ishinomaki we found children in evacuation centres huddled around kerosene lamps."

The charity said they met Kazuki Seto, eight, at an evacuation centre not far from Sendai. He told them: "We are really worried about the nuclear power plants. We are very afraid of nuclear radiation. That's why we don't play outside." Another, Yasu Hiro, 10, added: "We know about the bombs at Hiroshima and Nagasaki, and we are very scared. It makes us really worry. If it explodes it is going to be terrible."

New footage also emerged of the tsunami striking last Friday, filmed by a local reporter who fled to safety as the wave swept in. The footage showed a wave crashing down a street moments after he found safety on a staircase.

Buildings and cars were swept away, while a father and two children were stranded on the side of an upturned car. A woman clung to a tree. She was rescued using a fire hose. "Thank you. Thank you. I thought I was going to die," she said.