Part of Interstate 10 near downtown Los Angeles will remain closed indefinitely until repairs are made, officials said Sunday, putting Southern California commuters in a major bind this week after a massive fire rampaged through storage lots underneath the structure.

A large fire broke out under Interstate 10 Saturday after midnight, fully engulfing multiple pallets, vehicles, and trailers before winds blew the flames across the street to another storage yard, said Los Angeles Fire Department Chief Kristin Crowley. Eight acres were scorched in the blaze, officials said.

The California Department of Transportation sent officials to inspect the highway, and detours have been established in the area to ease traffic. Interstate 10, which runs east to west, has been closed in Los Angeles for at least 24 hours, according to authorities. The cause of the fire hasn't been released.

No people were reported injured. On Saturday night, California Gov. Gavin Newsom issued a state of emergency in Los Angeles County to deploy resources to repair the damage caused by the fire and minimize travel impacts for residents.

"This is one of those heaven and earth moments," Newsom said during a news conference Sunday afternoon in which he, Los Angeles City Mayor Karen Bass, and other officials provided updates about the fire. "This is a 24-7 operation full stop."

The interstate, which runs through the cities of Los Angeles, Long Beach, and Santa Ana, serves an average of 355,000 commuters each day and is among the top 25 most traveled locations in the country, according to the U.S. Department of Transportation.

Ongoing investigation into the cause of the blaze

Newsom said it is unknown when the freeway section will reopen but that he is aware of the impacts on schools and vulnerable communities. He said he is mindful of the urgency to reopen the freeway.

"We know the impact this fire will have on the surrounding communities as people need to drive to school, work and other activities," Bass said Sunday. "We are working day and night to make the repairs necessary to restore the freeway."

The blaze erupted in an industrial area, and no homes were damaged, officials said Sunday. Bass said about 16 unhoused people evacuated the area when the fire broke out but that there might be more displaced people. 

Bass said she spoke with U.S. Secretary of Transportation Pete Buttigieg on Saturday who assured her that federal resources will be available to help during the emergency.

Caltrans expects to complete its investigation into the cause of the fire by 6 a.m. Monday after structural engineers assess the damage to the freeway columns and the bridge deck, Newsom said during the news conference. Newsom added that "unless anything significant occurs," investigators may have an update then.

"I’m not going to understate the challenge here," California Transportation Secretary Toks Omishakin said Sunday. "It is significant … so this is not going to be an easy task for our structural engineers at Caltrans."

The governor did not provide many details about the investigation but said property owners were in violation of a lease, and officials are in current litigation.

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Newsom: LA freeway damage 'substantially greater' than I-95 collapse

Newsom on Sunday compared the emergency to the June collapse of Interstate 95 in Philadelphia, which was caused by a massive tanker truck fire that shut down the corridor in both directions.

"The scale of this is substantially greater; the question is: Is the damage substantially more problematic," he said during the press conference.

Philadelphia commuters faced delays, detours, and travel chaos in the days after the gasoline-hauling tractor-trailer flipped on an I-95 off-ramp on June 11. The damaged portion of the section was reopened ahead of schedule less than two weeks after the incident with six temporary lanes.

Newsom said emergency efforts are informed by best practices Pennsylvania officials mobilized in response to the disaster. 

At least 16 homeless people living underneath the highway were evacuated and brought to shelters, Bass said. Officials said there was no immediate indication that the blaze began at the encampment.

The mayor said the fire’s long-term impact could be reminiscent of damage from the Northridge earthquake that flattened freeways in 1994.

“Unfortunately, there is no reason to think that this is going to be over in a couple of days,” she said.

Alternate routes recommended

Doug Young, an assistant chief with the California Highway Patrol, said this section of I-10 is "one of the largest arteries" going in and out of Los Angeles. He said to expect long-term closures with officials providing daily updates on any changes to traffic routes.

According to the Los Angeles Emergency Management Department, the I-10 is closed in both directions, south of Downtown Los Angeles between the 110 Freeway and Alameda Street. Officials encouraged commuters to take alternate routes or use public transit options to avoid the closure entirely as repair work continues.

"Plan ahead for that Monday morning commute," the Los Angeles City Emergency Management Department advised on Sunday. "Check Metro Los Angeles for public transit options, or - if able - work from home until central area traffic impacts can be better assessed."

Contributing: The Associated Press