Los Angeles, California - Beaches in parts of Long Beach and Los Angeles were closed Friday after as much as six to seven million gallons of untreated sewage spilled into the Dominguez Channel, officials said.

Authorities said it's the largest sewage spill in LA County history.

"It is just flooding the street with fecal matter and toiletries just going down," a witness told ABC News of the mess.

"And the odor is really, really bad – contaminating our neighborhood."

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According to the city of Long Beach, the spill was caused by the failure of a 48-inch sewer main in Carson on Thursday. The channel runs into Los Angeles Harbor.

The closed beaches include Cabrillo, Port Fermin, White Point, Rancho Palos Verdes, and Royal Palms. They will remain closed until bacteria testing shows the water to be at safe levels. All swimming beaches in Long Beach are also closed, city officials said.

"For their safety, the community is encouraged to pay close attention to any warning signs posted at the beach," Long Beach said in a statement.

The Dominguez Channel was the site of another environmental crisis earlier this year. Beginning in October, thousands complained about a horrid smell coming from the creek that lasted for weeks.

Regulators later said a fire at a Carson warehouse that stored beauty and wellness products likely caused the foul odor.