The Madre Fire ignited Wednesday afternoon in San Luis Obispo County and has since grown to more than 35,500 acres, according to Cal Fire.

The fire sparked in the Los Padres National Forest in San Luis Obispo County and was growing exponentially, officials warned. The area is mostly uninhabited.

A wildfire in California’s San Luis Obispo County rapidly expanded overnight and was covering more than 52,600 acres by Thursday afternoon, prompting evacuation orders, closing part of a highway and sending thick smoke billowing into neighboring counties. It is the biggest wildfire the state has seen this year.