At least 1,200 people were evacuated on Saturday as a wildfire in Los Angeles County spread over thousands of acres near a major highway and threatened nearby structures, officials said.

The blaze, called the Post Fire, burned more than 3,600 acres (5.6 square miles or 14.5 square kilometers) near the Interstate 5 freeway in Gorman, about 62 miles (100 kilometers) northwest of Los Angeles, according to the California Department of Forestry and Fire Protection.

The Los Angeles County Fire Department said at 8 p.m. that the California State Park Service evacuated 1,200 people from the Hungry Valley Recreation Area in Gorman and that both the Hungry Valley and Pyramid Lake reservoirs were closed due to fire danger.

Officials said the fire broke out around 1:45 pm.

The fire department reported the fire was moving in a southeast direction toward Pyramid Lake and firefighters were building a perimeter fire line while aircraft worked to stop the fire’s progress despite limited visibility.