SAN DIEGO — The wildfires that have ravaged San Diego County since Tuesday have scorched more than 20,000 acres, fire officials said Friday.

The total acreage more than doubled Thursday, the most destructive day this week. The Cocos Fire went from 1,200 acres to 3,018 acres overnight, pushing from San Marcos into southwestern Escondido. Firefighters said cooler temperatures and lower winds helped them increase containment to about 10 percent. As of Friday night, the acreage had dropped to 2,520 acres as containment reached 50%.

The Pulgas Fire, which began Thursday afternoon on Camp Pendleton near Interstate 5 at Las Pulgas Road, burned about 8,000 acres by early Friday morning. It was 5 percent contained, Cal Fire said. A huge plume of black smoke rose from the blaze Friday and was carried inland by the prevailing winds. It could be seen for miles.

The Tomahawk Fire on Camp Pendleton had burned 6,500 acres and was 65 percent contained Friday. It and the Pulgas Fire account for more than half of the acreage burned in the county.

The Bernardo Fire has remained at at 1,548 acres since Tuesday, but as of Friday night it was 95 percent contained, Cal Fire said.

The other major fires, the Poinsettia in Carlsbad, the Freeway Fire near Fallbrook, the River Fire in Oceanside, and the Highway Fire north of Escondido, were 100 percent contained, according to Cal Fire.