GORMAN, Calif. (AP) — Strong winds pushed flames through dry brush in mountains along Interstate 5 north of Los Angeles, and officials warned residents in the wildfire’s path to be prepared to leave if it explodes in size again.

Los Angeles County’s first major wildfire of the year swiftly grew to nearly 23 square miles (60 square kilometers) on Sunday, one day after it forced the evacuation of at least 1,200 campers, off-roaders and hikers from the Hungry Valley recreation area.

The blaze, dubbed the Post Fire, was just 2% contained Sunday evening. No injuries were reported. The cause was under investigation.

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Firefighters working in sweltering conditions and steep terrain raced to douse spot fires that erupted as unpredictable winds blew embers ahead of the flames, said Kenichi Haskett, a section chief for the LA County Fire Department. The gusts also hampered efforts by aircraft crews to drop water and fire retardant, he said.

“When it’s windy, it just sprays the water everywhere we don’t need it. So that’s a challenge,” Haskett said.

Meanwhile in Northern California, a small wildfire sparked Sunday prompted evacuation orders and warnings for a sparsely populated area near Lake Sonoma. Known as the Point Fire, it sent up a huge plume of dark smoke as it churned through brush and timber about 80 miles (130 kilometers) north of San Francisco, and destroyed at least one structure. It was 15% contained.

The Southern California fire erupted Saturday afternoon near I-5 in Gorman, about 60 miles (100 kilometers) northwest of Los Angeles. Two structures burned within the evacuated recreation area.

Flames were moving toward Pyramid Lake, a popular destination for boaters that was closed as a precaution on Father’s Day. No houses were threatened Sunday, but officials warned residents of Castaic, home to about 19,000 people, that they should prepare to leave if the fire pushes further south.

“If you’re in a warning area, be prepared with a ‘go bag,’ with overnight clothes and your cellphone, your medicines, your glasses. Have your car fueled up,” said Haskett. “Be ready to evacuate.”

Low humidity and gusts around 50 mph (80 kph) were expected throughout the day, and winds could pick up speed after sundown, warned the National Weather Service office for Los Angeles.

About 75 miles (120 kilometers) to the east, the nearly 2-square-mile (5-square-kilometer) Hesperia Fire forced road closures and prompted evacuation warnings after it broke out Saturday near mountain communities in San Bernardino County. The blaze was 20% contained Sunday evening.

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Associated Press writer Christopher Weber in Los Angeles and radio reporter Julie Walker in New York contributed to this report.