Then-Lt. Gov. Gavin Newsom and President Donald Trump review destruction from wildfires in California on Nov. 17, 2018. Behind them is Gov. Jerry Brown. Trump has called for Newsom to resign over the wildfires that have scorched thousands of acres of land in Southern California and killed at least five people. Paul Kitagaki Jr.-Pool/Getty Images

President-elect Donald Trump early Thursday continued to fan the flames of the long-running feud between him and Gov. Gavin Newsom, blaming the devastating wildfires in Southern California on his "gross incompetence" and calling for the Democrat to step down.

"One of the best and most beautiful parts of the United States of America is burning down to the ground. It's ashes, and Gavin Newscum should resign. This is all his fault!!!" the incoming president posted on Truth Social.

In another, Trump said: "Nobody has ever seen such failed numbers before! Gross incompetence by Gavin Newscum and Karen Bass," referring to the mayor of Los Angeles who has taken heat over her initial absence as the wildfires began to spread.

Trump, who has clashed with the Blue State governor before on fire prevention, forest management and environmental issues, launched a broadside attack on Newsom on Wednesday, saying he was responsible for not signing a non-existent water restoration declaration.

"Governor Gavin Newscum refused to sign the water restoration declaration put before him that would have allowed millions of gallons of water, from excess rain and snow melt from the North, to flow daily into many parts of California, including the areas that are currently burning in a virtually apocalyptic way," Trump said. "He is the blame for this."

Newsom, in an interview Wednesday with CNN, accused the president-elect of turning a horrendous situation for thousands of people into a political attack point.

"People are literally fleeing," the governor said. "People have lost their lives. Kids lost their schools, families completely torn asunder, churches burned down. This guy wanted to politicize it."

The governor's office responded to Trump's claim about a water restoration declaration, saying it is "pure fiction."

"The Governor is focused on protecting people, not playing politics, and making sure firefighters have all the resources they need," spokesperson Izzy Gardon said.

Newsom declared a state of emergency over the fires on Tuesday, and President Joe Biden signed a federal major disaster declaration on Wednesday.

CalMatters, a nonprofit news site, published a fact check of Trump's claims, noting that he appeared to be referring to water "imported south from the Bay-Delta, fed by Northern California rivers and snowmelt. But most Los Angeles water does not come from Northern California."

Mark Gold, a board member of the Metropolitan Water District of Southern California, told the publication that Trump's comments fail to reflect the complex issues surrounding California's water supply.

"Tying Bay-Delta management into devastating wildfires that have cost people's lives and homes is nothing short of irresponsible, and it's happening at a time when the Metropolitan Water District has the most water stored in its system in the history of the agency," he said.