MIDDLETOWN, Calif. — Firefighters are reporting some progress against a Northern California wildfire that has charred more than 100 square miles of terrain, destroying buildings, threatening many others and sending thousands of residents fleeing.

As firefighters and equipment from outside the state poured in to battle the blaze burning about 100 miles north of San Francisco, more than 13,000 people were required or urged to leave their homes, vacation cabins and campsites.

Firefighting officials said crews made some progress Tuesday with some help from light rain. The blaze was 20 percent contained, but it was not expected to be corralled until at least Monday.

Teams were able to build a buffer between the flames and some of the estimated 6,900 homes it threatens. Despite the fire’s growth, no additional homes were consumed outside the two dozen already destroyed.

The fire, by far the largest of 11 burning in Northern California, started on July 29.