AKIPRESS.COM - Massive wildfires sweeping through California have killed at least 31 people and damaged thousands of homes, businesses and other buildings, ABC News reported citing authorities.

More than half of the deaths occurred in Sonoma County alone, officials said. Taken together, the death toll from this week's fires exceeds the number of fatalities in the 1933 Griffith Park Fire in Los Angeles, the deadliest wildfire in California history.

Firefighters were still battling 21 large wildfires in multiple counties as of Thursday morning. Intensified by strong winds, the flames have charred more than 190,000 acres of land, damaged or destroyed at least 3,500 structures and forced more than 20,000 residents to evacuate, according to the California Department of Forestry and Fire Protection.

Containment of the fire has increased, and weather conditions are expected to improve overnight, officials said Thursday.

The causes of the fires are still under investigation.