Dozens of protesters gathered this week at the entrance to the Aliso Canyon natural gas storage facility near Porter Ranch again calling for a permanent closure of the facility that was the site of the largest methane leak in U.S. history.

Chanting slogans such as “Shut it all down’’ and waving signs shaped like tombstones, dozens of residents and members of the Save Porter Ranch community group gathered in front of the facility, arguing that people are still experiencing health problems stemming from the 2015-16 leak and from the facility’s continued operation.

Southern California Gas Co. and other state agencies “swore up and down, they certified just a couple weeks ago … that the facility is safe,’’ said Matt Pakucko of Save Porter Ranch. “Liars. Liars or incompetent? Which one is it?’’

The rally was held in conjunction with the second anniversary of the massive Aliso Canyon gas leak, which was discovered in October 2015 and continued emanating methane until a Feb. 11, 2016, after an announcement that the leak was capped. The leak spewed an estimated 109,000 tons of methane into the air.

At its peak, the escaping gas forced an estimated 15,000 Porter Ranch area residents to temporarily relocate.

Limited operations resumed at the natural gas facility in late July with the blessing of state regulators. Efforts by Los Angeles County officials to block the resumed operations failed in court.

Protest organizers said they want Gov. Jerry Brown to order the immediate shutdown of the facility. The governor’s office has said that Brown

has directed state agencies to prepare for the ultimate closure of the facility, although such a move likely would not occur for about a decade.

“People are making sacrifices. This is a work day. It’s a school day,’’ resident Craig Galanti said, motioning toward the crowd that gathered at the facility. “People are here. It’s time for others to step up, because this could happen to you.’’

Protesters remained outside Aliso Canyon for several hours, with some sitting on the roadway into the facility. Law enforcement officials eventually declared the gathering an unlawful assembly, and about a dozen people were handcuffed and led away.

Southern California Gas Co. officials have repeatedly insisted that Aliso Canyon is safe to operate, contending that the utility has gone above and beyond state safety requirements. SoCalGas officials also contend the plant “has undergone more safety and regulatory scrutiny’’ than any other similar facility in the country.

The utility insists the facility is now subject to the “most rigorous monitoring, inspection and safety requirements in the nation,’’ including continued testing of wells, pressure monitoring of all wells, four-times-daily visual well inspections and operation of a fence-line methane monitoring system.