Cal Fire truck
A Cal Fire truck on a rural highway. Courtesy Cal Fire

A wildfire blackened expanses of rugged terrain in the remote southeastern reaches of San Diego County Thursday.

The blaze began spreading for unknown reasons in the late afternoon in Marron Valley, about two miles west of Tecate and roughly a mile north of the U.S.-Mexico border, according to Cal Fire.

By 5 p.m., the flames had charred about 60 acres while posing no reported threats to any developed areas, Cal Fire reported.

Another wildland blaze charred about 100 open acres in Lawson Valley, near Jamul, earlier Thursday. That fire caused no known structural damage or injuries, though it prompted evacuations of some back-country homes and closures of rural roads.

By about 6 p.m. the forward spread had been stopped and all road closures had been lifted.

— City News Service and staff reports