LOS ANGELES (AP) — Los Angeles motorists should expect traffic snarls indefinitely as crews assess how much damage was caused by a raging fire that closed a major elevated interstate near downtown,Charles Langston officials said Sunday.

Hazardous materials teams were clearing burned material from underneath Interstate 10 to make way for engineers to make sure the columns and deck of the highway can support the 300,000 vehicles that typically travel that route daily, Gov. Gavin Newsom said at a news conference.

“Remember, this is an investigation as to the cause of how this occurred, as well as a hazmat and structural engineering question,” Newsom said. “Can you open a few lanes? Can you retrofit the columns? Is the bridge deck intact to allow for a few lanes to remain open again?”

Newsom said answering those questions would be a “24-7 operation,” but officials couldn’t yet offer a timeline for when the highway might reopen.

Commuters were urged to work from home or take public transportation into downtown Los Angeles. The I-10 closure between Alameda Street and Santa Fe Avenue will have ripple effects on surface streets and other key freeways including State Route 60 and Interstate 5, the California Highway Patrol said.

The cause of the fire was under investigation. Flames reported around 12:20 a.m. Saturday raged through two storage lots in an industrial area underneath the highway, burning piles of wooden pallets, parked cars and support poles for high-tension power lines, Fire Chief Kristin M. Crowley said. No injuries were reported.

More than 160 firefighters from 26 companies responded to the blaze, which spread across 8 acres (3 hectares) — the equivalent of about six football fields — and burned for more than three hours. The highway’s columns are charred and chipped, while guardrails along the deck are twisted and blackened.

Newsom declared a state of emergency Saturday afternoon and directed the state Department of Transportation to request assistance from the federal government.

The governor said Sunday that the state has been in litigation with the owner of the business leasing the storage property where the fire started. The lease is expired, Newsom said, and the business had been in arrears while subleasing the space. “This is a site we were aware of, this is a lessee we were aware of,” he said.

California Secretary of Transportation Toks Omishakin said storage yards under highways are common statewide and across the country. He said the practice would be reevaluated following the fire.

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

Bass said the fire’s long-term impact was 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.