Firefighters are working furiously across California's famous wine country to contain more than a dozen wildfires that broke out over the Columbus Day weekend, causing at least 10 deaths, damaging more than 1,500 homes and businesses and forcing thousands to flee.

15 wind-whipped wildfires in nine counties burned more than 73,000 acres within 12 hours, according to local officials. While calmer winds helped emergency workers to contain the fires somewhat later in the day, emergency officials warned that anticipated gusts of wind – at times exceeding 50 miles per hour – could enable the wildfires to spread faster.

Photos: Wildfires in California Wine Country View All 19 Images

California Gov. Jerry Brown issued a state of emergency Monday, first in Napa, Sonoma, and Yuba Counties, and later added Butte, Lake, Mendocino, Nevada, and Orange counties as the wildfires continued to char the state.

“This is really serious. It’s moving fast,” Brown said Monday at a news conference. “The heat, the lack of humidity and the winds are all driving a very dangerous situation and making it worse. It’s not under control by any means. But we’re on it in the best way we know how.”

Later in the day Monday, the governor wrote to President Donald Trump for federal help as “this incident is of such severity and magnitude that an effective response is beyond the capabilities of the State and affected local governments and supplemental federal assistance is necessary.”

Napa and Sonoma counties are the source of some of the country’s best wines, with grapes planted on more than 100,000 acres of farmland. Producing 13 percent of the state's wines, the two counties are home to more than 650 wineries, according to the Wine Institute, a state industry group.