By Alex Dobuzinskis

LOS ANGELES (Reuters) - Firefighters had a Southern California wildfire mostly surrounded on Saturday, after making significant progress in cooler temperatures overnight on a blaze that has destroyed 105 homes and forced widespread evacuations, officials said.

The Blue Cut fire, named after a narrow gorge where it ignited about 75 miles (120 km) northeast of Los Angeles on Tuesday in an area called the Cajon Pass, has burned more than 37,000 acres (15,000 hectares) of drought-parched brush, said fire information officer Mike Lopez.

At its height, the blaze, which authorities called uncannily fierce, had forced authorities to order more than 80,000 residents to evacuate their homes. They also ordered the temporary closure of a segment of Interstate 15, which connects Las Vegas to the Los Angeles area, where it traverses the Cajon Pass.

But with the fire 68 percent contained, many residents were allowed to return home on Saturday, Lopez said.

Overnight, as the wind prevented the blaze from any dramatic growth, firefighters built strong containment lines near Wrightwood which allowed residents of that ski resort town to repopulate the area on Saturday, he said.

Residents of 7,000 other homes in the Cajon Pass area were still potentially in the fire's path and remained under evacuation orders, he said.

"We feel confident we can keep continuing this aggressive attack," Lopez said in a telephone interview.

Nearly 2,700 firefighters and crew were battling the wildfire, their efforts amplified by more than two dozen water-dropping airplanes and helicopters, according to tracking website InciWeb.gov.

Despite around-the-clock toil by firefighters, the blaze has destroyed 105 homes and 213 outbuildings, Lopez said.

The Blue Cut fire is one of nearly 30 major blazes that have burned some 530 square miles in eight Western states this week, as prolonged drought and unusually hot weather has intensified wildfire season, the National Interagency Fire Center in Boise, Idaho said.

(Additional reporting by Letitia Stein; Editing by Grant McCool)