SANTA BARBARA -- The massive wildfire burning northwest of Los Angeles became the fourth largest in California history, and authorities said it would likely keep growing and threatening communities as hot, gusty winds fanned the flames.

State officials said Thursday that the so-called Thomas Fire straddling coastal Ventura and Santa Barbara counties covered 242,500 acres (379 square miles). That surpassed a blaze that burned inland Santa Barbara County a decade ago. Officials said the blaze is 30 percent contained.

Cal Fire now confirms that one of its firefighters has died battling the Thomas Fire on Thursday morning.

The announcement came after reports of a “serious accident” that occurred as firefighters worked to contain the blaze on the outskirts of the town of Fillmore.

Some evacuations were lifted and the risk to the agricultural city of Fillmore was diminishing. But coastal enclaves to the west remained under threat as crews protected hillside homes in Montecito, Summerland and Carpinteria.

Schools were closed and many roads remained shut down. The USA Water Polo Women's National Team match against the Netherlands scheduled for Saturday in Santa Barbara was moved to Orange County.

The National Weather Service said extreme fire danger conditions could last through the weekend due to lack of moisture along with a likely increase in wind speeds. Gusts were expected to top 35 mph by midday Thursday.

Red Flag warnings now extend far north into the central Sierra Nevada.

Firefighters made some progress Wednesday on corralling the fire, which continued to spread mostly into national forest land.

Since the blaze broke out on Dec. 4, it has burned destroyed 970 buildings -- including at least 700 homes. Flames threatened some 18,000 buildings and prompted evacuations of about 100,000 people. It covers more ground than the city of San Diego.

To the south in San Diego County, firefighters came very close to containing another major wildfire a week after it broke out.

The Lilac Fire burned 4,100 acres and is 97 percent contained.

That fire burned down 157 structures, most in its destructive first hours. It also killed 46 race horses at a training center, and left one of their trainers with serious burns.

This post has been updated.