LOS ANGELES >> Los Angeles drivers were tested today during the first commute following a raging fire over the weekend that closed a major elevated interstate near downtown.

Many commuters appeared to have heeded warnings. TV news helicopter views generally showed less traffic than normal on some freeways encircling downtown but exits and area surface streets grew very crowded at the height of the commute.

“In looking at the traffic data earlier this morning, I am somewhat pleased to say that the congestion was a little bit lighter than normal,” said Rafael Molina, deputy district director for the division of traffic at the California Department of Transportation. “However, please — if you don’t need to be in downtown Los Angeles — please avoid those trips.”

Cellphones blasted a predawn reminder for residents to plan alternate commuting routes and to expect significant delays due to the fire’s impact on Interstate 10.

Hazardous materials teams were clearing burned material from underneath the elevated freeway to make way for engineers, who will ensure the columns and deck of the highway can support the 300,000 vehicles that typically travel that route daily, officials told a morning news conference. Temporary support structures were also being installed.

“Remember, this is an investigation as to the cause of how this occurred, as well as a hazmat and structural engineering question,” Gov. Gavin Newsom said at a news conference Sunday. “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 mile-long 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 remained under investigation. Flames reported around 12:20 a.m. Saturday ripped through two storage lots in an industrial area beneath the highway, burning parked cars, stacks of wooden pallets and support poles for high-tension power lines, fire Chief Kristin Crowley said. No injuries were reported.

More than 160 firefighters from more than two dozen companies responded to the blaze, which spread across 8 acres (3 hectares) — the equivalent of about six football fields — and burned for three hours. The highway’s columns are charred and chipped, and 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. Los Angeles Mayor Karen Bass said she had also talked with U.S. Secretary of Transportation Pete Buttigieg about any additional resources that may be needed.

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, 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.

LA residents have a history of responding well to advance warnings of traffic troubles. Warnings of “Carmageddon” for a full freeway closure in 2011 resulted in a widespread reduction in traffic. A predicted “Jamzilla” in 2014 proved not to be monstrous, and fears of massive traffic snarls failed to materialize during the 1984 Olympics.