The FBI is joining an investigation into a large oil spill off of California's southern coast, which caused Huntington Beach to close, due to thousands of gallons of crude oil that leaked from a pipeline owned by Houston-based firm Amplify Energy.

The FBI's Los Angeles office confirmed to Fox News Thursday in a rare confirmation that the office is joining other federal agencies in the investigation. 

"The FBI has joined an investigation into the Orange County oil spill near Huntington Beach, California, and is one of many federal agencies investigating to determine the cause of the rupture."

CALIFORNIA AG INVESTIGATING OIL SPILL THAT FORCED HUNTINGTON BEACH TO CLOSE

The California Department of Justice is also investigating the oil leak that sparked fears of an environmental disaster near Huntington Beach, California Attorney General Rob Bonta said on Monday.

"The oil spill off the coast of Huntington Beach is an environmental disaster with far-reaching consequences for our fish and wildlife, for our communities, and for our economy," Bonta said in a press release. "I want to thank all our local, state, and federal partners who are working around the clock to protect the health and safety of Californians and to mitigate the damage to our environment and natural resources."

Bonta reportedly has not said whether the investigation is criminal or civil. The Orange County district attorney’s office and the U.S. Coast Guard are also looking into the environmental disaster.

Officials said the leak may have occurred after a ship’s anchor caused damage to the pipeline, but authorities have yet to announce a definitive finding. The Coast Guard estimates between 25,000-132,000 gallons of crude oil leaked into the ocean. 

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Many Democrats have called for the end to offshore drilling in the aftermath of the spill.

The Los Angeles area is also facing other crises including a supply chain bottleneck at two large ports and a fire that broke out on shipping containers due to the congestion.

Fox News' Thomas Barrabi contributed to this report.