Los Angeles prosecutors filed misdemeanor criminal charges Tuesday against a utility for failing to immediately report a natural gas leak that has been gushing nonstop for nearly 15 weeks.

District Attorney Jackie Lacey said the charges aren't a solution to the problem, but Southern California Gas Co. needs to be held responsible for the leak that has uprooted more than 4,400 families.

The charges came the same day the state attorney general joined a long line of others in suing the gas company for the blowout that has spewed more than 2 million tons of climate-changing methane since October.

U.S. senators want the secretary of energy to investigate the leak, and federal regulators are crafting new safety standards for underground natural gas storage facilities. Many nearby residents want the facility — the largest in the West — shut down, and the California Public Utilities Commission is studying what impact that would have on energy supplies.

The criminal complaint charges the company with three counts of failing to report the release of a hazardous material and one count of discharge of air contaminants.

The company said in a statement that it will vigorously defend itself in court. Arraignment is scheduled Feb. 17.

If convicted, the company could be fined up to $1,000 per day for air pollution violations and up to $25,000 for each of the three days it didn't notify the state Office of Emergency Services of the leak.

The company said it discovered the leak Oct. 23 and notified state regulators.

But it failed to let state emergency officials know until Oct. 26, Attorney General Kamala Harris said in the latest of more than two dozen lawsuits filed against SoCalGas.

The public was also left in the dark. Those who complained to the company about the nauseating smell were initially told it was part of routine maintenance. Company officials have since apologized for not notifying them sooner.

The leak has created a public health and statewide environmental emergency, Harris said. The lawsuit, which doesn't specify damages, said the company created a nuisance and violated health and safety codes and the state's unfair competition law.

A spokeswoman said the company doesn't comment on pending litigation and was focused on stopping the leak, which it expects to plug by the end of the month.

SoCalGas said it paid $50 million through December to try to cap the leak and relocate people, but the number of families it has relocated since then has soared and work at the leaking well continues.

It is also facing potential class-action lawsuits from residents and businesses as well as suits from regional air regulators and city and county authorities.

Harris, a Democrat running for U.S. Senate, is the first state official to sue, though her lawsuit incorporates some elements of lawsuits filed by the city and county of Los Angeles.

Several state agencies are investigating the blowout and have issued orders to the gas company to stop it and turn over records of the 60-year-old well and others from the field that is the largest natural gas storage facility in the West.

The federal Pipeline and Hazardous Materials Safety Administration got involved for the first time Tuesday, saying it is working to propose new regulations for gas storage and directing operators to "inspect and take immediate actions to ensure the safety of underground natural gas storage facilities across the country."

U.S. Rep. Brad Sherman, a Democrat who lives in the Porter Ranch neighborhood that has been most affected by the gas leak, said the agency's advisory amounted to a note to industry saying, "not just please, but pretty please" follow the American Petroleum Institute's recommended practices for gas storage.

"At a very minimum, those practices should be mandatory immediately," said Sherman, who is working on legislation that would require PHMSA to set safety standards for natural gas storage facilities.

The agency's advisory said gas storage operators should check for leaks and identify potential failures from corrosion and other damage. The agency said the SoCalGas gas leak probably came from a well casing.

State regulators are investigating the cause of the leak, but they said they won't know until the well is plugged.

Residents have reported maladies that include headaches, nosebleeds, rashes and other woes.

Public health officials have blamed the symptoms on odorants added to make the gas detectable. They have said the leak — mostly methane but including trace elements of the carcinogen benzene — is not expected to cause long-term health problems.

California Sens. Barbara Boxer and Dianne Feinstein, both Democrats, introduced a legislative amendment passed Tuesday that would ask the U.S. Department of Energy to investigate and stop the Aliso Canyon leak and prevent similar disasters at the nation's more than 400 underground natural-gas storage sites.

Boxer stood by a dramatic infrared photo that showed the otherwise invisible plume of methane-laced natural gas from the blowout. She told fellow senators in a speech on the Senate floor that the leak was a "nightmare."