TOKYO >> Engineers tried to stem a leak of highly radioactive water spilling into the Pacific with a new method Sunday after concrete failed to seal the crack at a Japanese nuclear power plant incapacitated by last month’s earthquake-spawned tsunami. A search of site found no other leaks.

The wave has carved a path of destruction up and down the northeastern coast and is believed to have killed 25,000 people. The first deaths at the Fukushima Dai-ichi nuclear plant itself, though, were confirmed Sunday by the operator. A 21-year-old and a 24-year-old were conducting regular checks at the complex when the 9.0-magnitude earthquake hit March 11.

“It pains us to have lost these two young workers who were trying to protect the power plant amid the earthquake and tsunami,” Tokyo Electric Power Co. Chairman Tsunehisa Katsumata said in a statement.

The bodies were not discovered until Wednesday and had to be decontaminated. The announcement was delayed while authorities notified their families, TEPCO spokesman Kazufumi Suzuki said.

Since the tsunami knocked out the plant’s cooling systems and reactors began to dangerously overheat, a series of almost daily problems has led to substantial amounts of radiation leaking into the atmosphere, ground and sea in the world’s worst nuclear crisis since the 1986 meltdown at Chernobyl in the former Soviet Union.

On Saturday, authorities discovered a crack from which radioactive water was spilling into the Pacific — the first time they identified a direct source of sea contamination. The ultimate source of the water is believed to be the reactor cores.

A picture released by TEPCO shows water shooting some distance away from a wall and splashing into the sea, though the amount of water was not clear. The contaminated water will quickly dissipate in the ocean but could pose a danger to workers at the plant.

The 8-inch- (20-centimeter-) long crack is in a maintenance pit from which water containing levels of radioactive iodine far above the legal limit spilled into the ocean, said Hidehiko Nishiyama of Japan’s Nuclear and Industrial Safety Agency.

Workers filled the pit with concrete but couldn’t get it to dry.

Next, they injected polymer into a pipe that connects the pit to the rest of the system. The polymer can absorb enormous amounts of water and expands 50 times its original size. It’s not yet known if that stemmed the leak.

The crack is believed to have been caused by the earthquake, though that is still under investigation. The reactor buildings and other structures in more sensitive parts of the plant are build to stricter codes and thus are better able to withstand earthquakes than the pit was, according to Nishiyama.

“Even if a crack in the pit is caused by the quake, the reactors must have withstood the temblor,” he said.

Over the past 10 days, pooling water at the nuclear complex has repeatedly forced technicians to pull back and suspend their work.

A search of the plant Sunday found no other similar leaks leading directly to the ocean. “We believe that’s the only crack,” said another TEPCO spokesman, Naoki Tsunoda.

People living within 12 miles (20 kilometers) of the plant have been evacuated, but, as with previous leaks, it could pose a danger to workers.

Radiation — as well as debris and several explosions — slowed the search for the bodies of the two workers who have been listed as missing since just after the quake struck.

The two were last seen in a control room at one of the reactors. It’s not clear why they didn’t evacuate.

But it was thought that following the quake, the men ran to the basement of a turbine building. Workers have been trying to get access to that area since and successfully drained enough water last week to find the bodies.

The nuclear crisis has compounded the suffering of people in the northeast and, at times, overshadowed their plight. Tens of thousands have lost their homes and are living in shelters, 200,000 households do not have water, and 170,000 do not have electricity.

Running water was just restored in the port city of Kesennuma on Saturday, and locals lined up Sunday to see a dentist who had flown in from the country’s far north to offer his services. Many of the residents were elderly and complaining of problems with their dentures.

Overhead and throughout the coastal region, meanwhile, helicopters and planes roared by as U.S. and Japanese forces finished their all-out search for bodies.

The effort, which ends Sunday, is probably the final hope for retrieving the dead, though limited operations may continue. It has turned up nearly 50 bodies in the past two days.

In all, 12,000 deaths have been confirmed, and another 15,400 people are missing.