FORT BRAGG, Calif. — A firefighter was killed Monday while battling California's Mendocino Complex Fire, marking the first death in the largest wildfire in recorded state history.

California Department of Forestry and Fire Protection, or Cal Fire, Chief Sean Kavanaugh confirmed in a news conference late Monday night that a firefighter from Utah died from injuries sustained while "working on an active portion of the fire."

The firefighter, who was not identified, was airlifted to a local hospital where he died from his injuries, Kavanaugh said, adding, "We are extremely heartbroken from this loss."

A wildfire burns near homes in the Cleveland National Forest in Lake Elsinore, Calif on Aug. 9, 2018. Ringo H.W. Chiu / AP

The fatality marked the 11th in an unusually dangerous fire season that officials described Saturday as "a siege."

The Mendocino Complex fire, which began on July 27, includes two blazes, the Ranch and River fires, that have scorched nearly 350,000 acres across the rural northern counties of Colusa, Lake and Mendocino.

The fire was nearly 68 percent contained as of Monday night and had destroyed 146 homes and 118 other buildings, according to Cal Fire data. More than 1,000 structures remain threatened.

Thousands of fire personnel were battling the blaze using hundreds of fire engines, helicopters and dozers.

"Today’s events are definitely a tragedy, and they’re not expected and they’re not wanted," Lake County Sheriff Brian Martin said. "But they’re a stark reminder of how dangerous this career is."