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 of dark smoke blanketing the area.

The fire began Thursday evening, and the cause is under investigation.

About 500 firefighters were battling the blaze, supported by water-dropping helicopters that hovered over homes and hillsides, along with aircraft.

Firefighters said the blaze had the “potential for large fire growth” in the next 12 hours.

The fire produced coiling clouds of dense smoke, and flames could be seen cresting hillside ridges.

No injuries were reported, and no homes or other structures had been damaged or destroyed.

The National Weather Service said downtown Los Angeles hit a high of 112 degrees Fahrenheit on Friday, which marked the third time since 1877 that a high of 112 degrees or more has been reached there.