Officials warned of an “environmental catastrophe” on Sunday after more than 120,000 gallons of oil leaked from a rig and washed up on beaches south of Los Angeles, threatening wildlife and closing popular shores.

Shortly before midnight local time, officials had yet to confirm that the leak had been fully stopped, said Petty Officer Richard Brahm, a spokesman for the Coast Guard, adding that the oil rig was still being evaluated.

The oil spill, a few miles offshore from Newport Beach and Huntington Beach, was first reported Saturday and leaked about 126,000 gallons spanning 13 square miles, officials said. The emergency sent people scrambling to contain the fallout and protect sensitive habitats.

“This oil spill constitutes one of the most devastating situations that our community has dealt with in decades,” Huntington Beach Mayor Pro Tem Kim Carr said during a news conference on Sunday. She said authorities are looking at how to hold accountable the responsible parties and warned there will be “a lot more hitting our shores over the next few days.”

Laguna Beach closed its beaches at 9 p.m. on Sunday, while the state Department of Fish and Wildlife issued an order closing fisheries from Huntington Beach through Newport Beach and Laguna Beach down to Dana Point, saying that fishing was prohibited in the vicinity of the spill and where the spill was anticipated to spread.

The Coast Guard said on Sunday evening that over 5,300 feet of floating barriers, known as booms, had been deployed and that approximately 3,150 gallons of oil had been recovered from the water.

But oil still “infiltrated” and caused damage in a wetlands area called Talbert Marsh, which is home to many bird species, according to Orange County Supervisor Katrina Foley. The county is building a sand berm to keep the oil from intruding further, Foley said on Sunday.

The damage to wildlife is still emerging. While Foley said dead birds and fish started to wash ashore, other officials said they could only confirm that one duck was “oiled” and is getting veterinary care. “We’re hoping we have minimal impact, but we’re preparing for the worst,” said Christian Corbo, a lieutenant at the California Department of Fish and Wildlife.

Authorities said the oil came from Platform Elly, a pipeline operated by Beta Offshore, a Long Beach unit of Houston’s Amplify Energy. Speaking Sunday alongside officials from the responding agencies, Amplify Energy chief executive Martyn Willsher said that the company is investigating the spill and that divers were at a potential source site of the leak.

He said the pipeline has been “meticulously maintained” throughout the ownership by Amplify and was “suctioned at both ends” to prevent more leaking. “Everything is shut down,” Willsher said. “Our employees live and work in these communities, and we’re all deeply impacted and concerned about the impact,” the executive said, adding, “We will do everything in our power to ensure that this is recovered as quickly as possible.”

Huntington State Beach was closed, while the final day of a popular air show that drew 1.5 million visitors to area shores Saturday was canceled. Meanwhile, the city of Huntington Beach also closed much of its ocean and shoreline, officials said. Orange County Health Officer Clayton Chau urged people against swimming or even gathering on the affected beaches and warned that vapors from the oil spill could spread on the wind.

Rep. Michelle Steel (R-Calif.) sent a letter to President Biden seeking major disaster declaration for Orange County, while local leaders said the booms aimed at containment could stay in place for weeks or months.

“It is imperative that the Federal Government assist in recovery efforts. Constituents who live along the shoreline are already reporting oil on the beach and strong odors,” Steel wrote. “I have serious concerns about the environmental impacts of the spill and applaud the workers who are doing their best to prevent the oil from hitting sensitive wetlands.”

Officials Sunday night said over 3,000 gallons of oily water were recovered and nine boats dispatched. Sean Anderson, a coastal ecotoxicologist who leads an environmental science and resource management program with California State University, said the primary concern will be the impact on beaches, wetlands and animals. “The animals most affected, that we can’t do anything about, are those critters just offshore. Those are going to be seabirds, marine mammals, things of that nature,” Anderson said. Some animals, like dolphins, can swim out of the way if they see oil.

But Anderson said seabirds are vulnerable. If they land on water in the area of the leak, the oil could splash on them. The birds maintain their warmth by having clean feathers, so their instinct is to preen or clean the oil off, “as if it’s a piece of dirt. Then they ingest the oil and if it’s a little, it might be okay, but it’s usually a pretty toxic exposure, and they die.”

He said sand crabs that live right where the waves break on the face of the beach will also be heavily harmed. “Everybody eats those things. Fish eat them, birds eat them. They are really super important for the sandy beach ecosystem,” Anderson said. While the environmental impact may still be problematic, he said “in the grand scheme of things, it’s a relatively small amount of oil in terms of many of our offshore oil spills.”

“Certainly nobody should be eating fish from this immediate area right now, nobody should be swimming in it,” Anderson said. He said the toxicity will fade “fairly quickly,” but the “biggest concerns are in the immediate hours and days right after the oil gets released.”

The largest oil spill recorded in the waters off California was near Santa Barbara in 1969. An estimated 80,000 to 100,000 barrels of crude oil over 10 days and killed some 3,500 seabirds, as well as marine animals such as dolphins and sea lions. It evidently provided the inspiration for Earth Day. The oil spill over the weekend amounts to about 3,000 barrels.

The California Department of Fish and Wildlife said it sent surveillance and cleanup crews to the area, and the Oiled Wildlife Care Network at the University of California at Davis said it had deployed a number of staff members to support response efforts in the Newport Beach area.

Newport Beach officials advised residents to avoid contact with ocean water and parts of the beach where oil could be seen. The city said its beaches would remain open to the public but urged caution. Residents were urged to call a hotline if they spot wildlife affected by the oil.

Krysta Higuchi, a spokesperson for the Pacific Marine Mammal Center in Laguna Beach, said the group is prepared to treat marine mammals but had not yet received reports of any affected by the spill. “It’s all hands on deck, but it’s still a waiting game as we don’t know the full extent of the issue,” she said, adding it may take weeks before harmed wildlife washes ashore. “We’re just preparing for the worst but hoping for the best.”