FUKUSHIMA, Japan — Workers at a leaking nuclear complex hooked up power lines to all six of its reactor units, but other repercussions from a massive earthquake and tsunami still rippled across Japan as economic losses mounted at three flagship companies.

The progress on the electrical lines at the Fukushima Dai-ichi nuclear power plant was a welcome and significant advance Tuesday after days of setbacks. With the power lines connected, officials hope to start up the overheated plant’s crucial cooling system that was knocked out during the March 11 earthquake and tsunami that devastated Japan’s northeastern coast.

Tokyo Electric Power Co. warned that workers still need to check all equipment for damage first before switching the cooling system on to all the reactor units — a process that could take days or even weeks.

Late Tuesday night, Tokyo Electric said lights went on in the central control room of Unit 3, but that doesn’t mean power had been restored to the cooling system. Officials planned to try to power up the unit’s water pumps later today.

Emergency crews also dumped 18 tons of seawater into a nearly boiling storage pool holding spent nuclear fuel at Unit 2, cooling it to 105 degrees Fahrenheit, Japan’s nuclear safety agency said. Steam, possibly carrying radioactive elements, had been rising for two days from the reactor building, and the move lessens the chances that more radiation will seep into the air.

Added up, the power lines and concerted dousing bring authorities closer to ending a nuclear crisis that has complicated the government’s response to the catastrophic earthquake and tsunami that killed an estimated 18,000 people.

Its power supply knocked out by the disasters, the Fukushima complex has leaked radiation that has found its way into vegetables, raw milk, the water supply and even seawater. Early today, the government added broccoli to the list of tainted vegetables, which also include spinach, canola, and chrysanthemum greens. Government officials and health experts say the doses are low and not a threat to human health unless the tainted products are consumed in abnormally excessive quantities.

The Health Ministry ordered officials in the area of the stricken plant to increase monitoring of seawater and seafood after elevated levels of radioactive iodine and cesium were found in ocean water near the complex. Education Ministry official Shigeharu Kato said a research vessel had been dispatched to collect and analyze samples.

The crisis continued to batter Japan’s once-robust economy.

Three of the country’s biggest brands — Toyota Motor Corp., Honda Motor Co. and Sony Corp. — put off a return to normal production due to shortages of parts and raw materials because of earthquake damage to factories in affected areas.

Toyota and Honda said they would extend a shutdown of auto production in Japan that already is in its second week, while Sony said it was suspending some manufacturing of popular consumer electronics such as digital cameras and TVs.

The National Police Agency said the overall number of bodies collected so far stood at 9,099. An additional 13,786 people have been listed as missing, though there may be some overlap on those two lists.

“We must overcome this crisis that we have never experienced in the past, and it’s time to make a nationwide effort,” Chief Cabinet Secretary Yukio Edano, the government’s public point-man, said Tuesday in his latest attempt to try to soothe anxieties.

Still, tensions were running high. Officials in the town of Kawamata, about 30 miles from the reactors, brought in a radiation specialist from Nagasaki — site of an atomic bombing during World War II — to calm residents’ fears.

“I want to tell you that you are safe. You don’t need to worry,” Dr. Noboru Takamura told hundreds of residents at a community meeting. “The levels of radiation here are clearly not high enough to cause damage to your health.”

But worried community members peppered him with questions: “What will happen to us if it takes three years to shut down the reactors?” “Is our milk safe to drink?” “If the schools are opened, will it be safe for kids to play outside for gym class?”

While many of the region’s schools, gymnasiums and other community buildings are packed with the newly homeless, in the 11 days since the disasters the numbers of people staying in shelters has halved to 268,510, presumably as many move in with relatives.

In the first five days after the disasters struck, the Fukushima complex saw explosions and fires in four of the plant’s six reactors, and the leaking of radioactive steam into the air. By Tuesday, 1,000 plant workers, subcontractors, defense troops and firefighters were at the scene, the Nuclear and Industrial Safety Agency said.