LOS ANGELES (AP) — After weeks of windy and dry weather, rain has fallen in parched Southern California and is expected to aid firefighters who are mopping up multiple wildfires. But potentially heavy downpours on charred hillsides could bring new troubles such as toxic ash runoff.

Los Angeles County crews spent much of the past week removing vegetation, shoring up slopes and reinforcing roads in devastated areas of the Palisades and Eaton fires, which reduced entire neighborhoods to rubble and ash after breaking out during powerful winds Jan. 7.

Most of the region was forecast to get around an inch (about 2.5 centimeters) of precipitation over several days, but “the threat is high enough to prepare for the worst-case scenario” of localized cloudbursts causing mud and debris to flow down hills, the National Weather Service said on social media.

“So the problem would be if one of those showers happens to park itself over a burn area,” weather service meteorologist Carol Smith said. “That could be enough to create debris flows.”

Rainfall that began late Saturday was expected to increase Sunday and possibly last into early Tuesday, forecasters said. Flood watches were issued for some burn areas, while snow was likely in the mountains.

Los Angeles Mayor Karen Bass issued an executive order last week to expedite cleanup efforts and mitigate the environmental impacts of fire-related pollutants. LA County supervisors also approved an emergency motion to install flood-control infrastructure and expedite and remove sediment in fire-impacted areas.

Fire crews filled sandbags for communities, while county workers installed barriers and cleared drainage pipes and basins.

Officials cautioned that ash in recent burn zones was a toxic mix of incinerated cars, electronics, batteries, building materials, paints, furniture and other household items. It contains pesticides, asbestos, plastics and lead. Residents were urged to wear protective gear while cleaning up.

Concerns about post-fire debris flows have been especially high since 2018, when the town of Montecito, up the coast from LA, was ravaged by mudslides after a downpour hit mountain slopes burned bare by a huge blaze. Hundreds of homes were damaged and 23 people died.

While the impending wet weather ended weeks of dangerous gusts and reduced humidity, several wildfires were still burning Saturday across Southern California. Those included the Palisades and Eaton fires, which killed at least 28 people and destroyed more than 14,000 structures. Containment of the Palisades Fire reached 81% on Saturday and the Eaton Fire was 95% contained.

In northern Los Angeles County, firefighters made significant progress against the Hughes Fire, which prompted evacuations for tens of thousands of people when it erupted on Wednesday in mountains near Lake Castaic.

In San Diego County, there was still little containment of the Border 2 Fire as it burned through a remote area of the Otay Mountain Wilderness near the U.S.-Mexico border.

The rain was expected to snap a near-record streak of dry weather for Southern California. Much of the region has received less than 5% of the average rainfall for this point in the water year, which began Oct. 1, the Los Angeles Times reported Saturday.

Most of Southern California is currently in “extreme drought” or “severe drought,” according to the U.S. Drought Monitor.

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The CIA has concluded that Covid-19 probably began as a leak from a laboratory in China in a new assessment of the origins of the pandemic that killed millions of people.

The US intelligence agency said it concluded with “low confidence” that the Covid-19 virus had leaked from the research facility, in a shift of its previous position that there was insufficient information to reach a conclusion.

“CIA assesses with low confidence that a research-related origin of the COVID-19 pandemic is more likely than a natural origin based on the available body of reporting,” the agency said in a statement on Saturday.

“CIA continues to assess that both research-related and natural origin scenarios of the COVID-19 pandemic remain plausible.” 

The US intelligence community — which is made up of 18 agencies — has been assessing the origin of Covid-19 for the past four years to determine if the virus emerged naturally from a wet market in Wuhan or whether it leaked from the Wuhan Institute of Virology in the Chinese city.

The CIA joins the FBI and energy department in concluding that the virus originated from the Wuhan lab. But it said it had “low confidence in this judgment” and would “continue to evaluate any available credible new intelligence reporting or open-source information” that could change its assessment.

The new assessment was made public just days after John Ratcliffe was sworn in as CIA director.

In an interview with Breitbart news after he was confirmed as President Donald Trump’s pick to lead the intelligence agency, Ratcliffe said he believed that intelligence and common sense “dictates that the origins of Covid was a leak at the Wuhan Institute of Virology” and would ensure that “the public is aware that the agency [CIA] is going to get off the sidelines”.

One US official said Bill Burns, CIA head during the Biden administration, had told the CIA team assessing the evidence to take a position on the origin of Covid-19, but did not dictate the outcome.

Burns’ directive came as Jake Sullivan, who served as national security adviser, ordered the intelligence community to take another look at the origins of the pandemic as the Biden team prepared to leave office.

The US official stressed that the CIA had revised its assessment before Ratcliffe was sworn in as the new director.

“I’ve said from the beginning that Covid likely originated in the Wuhan labs. Communist China covered it up and the liberal media covered for them, said Tom Cotton, the Republican head of the Senate intelligence committee.

“I’m pleased the CIA concluded in the final days of the Biden administration that the lab-leak theory is the most plausible explanation of Covid’s origins, and I commend Director Ratcliffe for fulfilling his promise to release this conclusion. Now, the most important thing is to make China pay for unleashing a plague on the world.”

The Chinese embassy in the US did not respond to a request for comment.

The new CIA assessment change comes just over one week after Trump held his first phone call with Chinese President Xi Jinping since at least 2021. While many foreign policy experts had expected Trump to take a tough line on China — particularly over trade — in his first week in office, the president has so far held off taking any harsh measures against Beijing.

In an interview with Fox News this week, Trump said that while tariffs gave him “tremendous power” over China, he would “rather not have to use it”.

He also signed an executive order postponing the deadline for the Chinese owner of TikTok to divest the popular video app to avoid a ban in the US.