SAN BERNARDINO, Calif. — Evacuations were expanded Saturday as a wildfire with leaping flames scorched the foothills of a national forest east of Los Angeles, amid a days-long heat wave that pushed temperatures into the triple digits across the region.

The so-called Line Fire was burning uncontrolled along the edge of the San Bernardino National Forest, about 65 miles east of L.A. As of Saturday afternoon, the blaze charred about 11 square miles of grass and chaparral, leaving a thick cloud…