LOS ANGELES: A blowout at a natural gas well that leaked uncontrollably for 16 weeks and drove thousands of residents from their Los Angeles homes was plugged Thursday, a utility said.

While the well still needs to be permanently sealed with cement and inspected by state regulators, the announcement by Southern California Gas Co. marked the first time the massive leak has been under control since it was reported October 23.

"We've achieved control of the well today," said Jimmie Cho, a SoCalGas senior vice president. He said he was very confident they would complete the job.

The leak is expected to cost the company, a division of Sempra Energy, $250 million to $300 million, according to a filing with the Securities and Exchange Commission.

That figure could climb much higher because it only accounts for costs of capping the well, lost gas and relocating families. It does not include potential damages from more than 65 lawsuits, penalties from government agencies and expenses to mitigate pollution, which the company noted could be significant.

If the plug holds and all goes according to plan to seal the well, the upscale Porter Ranch community in the San Fernando Valley could begin to return to normalcy after schools were closed and 6,400 families were uprooted as they complained of headaches, nausea, nosebleeds and other symptoms as an intermittent stench wafted through the area.

Public health officials blamed their woes on an odorant added to gas so it can be detected and have said they don't expect long-term health impacts.

Vicky Walker, who lives close to the facility, said the smell was particularly strong the past few nights but wasn't noticeable Thursday afternoon.

She spent three to four nights a week in a hotel after developing a cough, but returned regularly to work from her home office. But she gained five pounds as she stayed inside as much as possible and stopped walking her dog.

"I want to get back to life as I knew it as soon as possible," Walker said. "And I hope property values don't suffer."

The leak at the largest underground gas storage reservoir in the West was declared an emergency by the governor. At its peak, the leak was estimated to contribute about a quarter of the state's climate-altering methane emissions, leading some to call it the worst environmental disaster since the 2010 BP oil spill in the Gulf of Mexico.

While the gas was invisible, its impact could be seen in half-vacant subdivisions, two shuttered schools and on the faces of angry residents who packed public meetings and community forums and demanded the Aliso Canyon storage facility be shut down.

The blowout happened in a 60-year-old well that was built to pump oil from porous rock a mile-and-a-half below the Santa Susana Mountains. After the oil ran dry in the 1970s, the field of 115 wells was reused to store natural gas.

When demand and prices were low, gas was injected at high pressure in the ground. It was piped out during cold months or to fuel gas-run electricity plants during energy spikes.

High-tech equipment will be used to survey the ruptured pipe for clues about what went wrong after it is permanently sealed.

Residents who voluntarily moved out will have at least a week to return to their homes after inspectors use a five-step process to certify it is safe.

SoCalGas has paid to relocate residents in hotels, apartments and houses. Hotel dwellers will have eight days to return home and those who moved to other accommodations can stay through the end of short-term leases they signed.

In recent weeks, 1,700 families have returned home as the rate of the leak dwindled and air filters were installed in their homes, the company said.

Once the well is sealed, though, life for some may never return to normal. The incident has focused attention on the aging facility and the state is investigating how Southern California would replace a major source of energy if it is shut down forever.

Many folks are concerned about plummeting home values now that Porter Ranch is associated with this disaster and others fear returning to unhealthy homes or a repeat incident.

"Because this one well we know about is shut down, it doesn't indicate anything about the rest of the facility," said Matt Pakucko, president of Save Porter Ranch, a group advocating to shutter the facility. "People are terrified to go home."