Firefighters in Tehama County, California, continued to battle the Park Fire on Tuesday, as the massive blaze had reignited and resumed spreading widely on Monday—growing by as much as 20 square miles.

The Park Fire, California’s largest this year and the state’s fourth-largest on record, had already scorched nearly 647 square miles by Tuesday morning. The inferno was allegedly caused by arson outside the city of Chico on July 24.