LOS ANGELES — A six-day-old wildfire that has destroyed 74 buildings and churned through more than 105,000 acres of mountainous brush showed little sign of slowing yesterday, and fire officials offered little hope of containment as long as hot, dry conditions continued.

The Station Fire, the largest of several burning in California, was plowing through dense hillside vegetation along the San Gabriel Mountains, cutting a swath that extended from Altadena into the high desert. Yesterday, the fire advanced to the west, bringing new evacuations to Sunland-Tujunga and coming within a few miles of Santa Clarita.

On the fire's eastern flank, officials were still hoping a concerted effort to hack away tree limbs, cut fire breaks and lay down fire retardant would spare the Mount Wilson Observatory and a complex of communications towers, used for broadcasting by nearly 50 radio and television stations.

Despite the sprawling dimensions of the fire, stretching up to 25 miles from east to west and 18 miles north to south, ground and aerial firefighting assaults managed to contain the blaze to largely undeveloped areas.

"There have been hundreds of homes saved in this effort," Los Angeles County Deputy Fire Chief Mike Bryant said.

But the outlook for the coming days remains "treacherous," said Mike Dietrich, incident commander for the U.S. Forest Service. "This is a very angry fire. Until we get a change in the weather conditions, I am not overly optimistic. The fire is headed just about anywhere it wants."

High fire danger conditions were expected to increase the risk the blaze could reach new communities in the Antelope, Santa Clarita and San Gabriel valleys. More than 6,000 homes were under mandatory evacuation orders related to the Station Fire alone. Full control was not expected until well after Labor Day, even as the number of firefighters on the lines swelled to more 3,700.

Losses from the fire spiked yesterday when officials discovered 53 cabins, homes and other structures destroyed in the remote Big Tujunga Canyon area. Officials estimated multimillion-dollar losses but stressed they were still tallying the destruction as inspectors reached burned areas.

Weary fire crews that were trading 12-hour shifts had little time yesterday to mourn the deaths of two Los Angeles County firefighters killed Sunday when their truck overturned on a mountain road.

The pair — Capt. Tedmund Hall, 47, and firefighter specialist Arnaldo Quinones, 35 — were part of a team of 65 firefighters trying to defend a fire camp, when flames made a sudden run at their positions, said Los Angeles County Fire Chief P. Michael Freeman. Preliminary indications are that Hall and Quinones were trying to reposition a fire truck that tumbled 800 feet down a steep slope. Other firefighters suffered minor injuries in a rescue effort, Freeman said.

MOUNT WILSON BLAZE

At Mount Wilson, the intensity and unpredictability of the blaze, which continued shifting directions, forced fire crews to pull back from the mountaintop and wait for the firestorm to pass. With the blaze burning on both sides of the only access road to the complex, firefighters could become trapped if the inferno suddenly raced up the canyon walls.

"Right now, the fire is boss," said Larry Peabody, division supervisor trainee for the U.S. Forest Service. "We're experiencing rates of spread of fire in excess of 15 miles per hour, flame lengths in excess of 100 feet and very limited access to the fire."

The drama of families having to flee their homes — or risking all to try to defend their property — played out repeatedly as searing heat and a generation of accumulated hillside growth fed the fires.

There was confusion and concern when six people refused to evacuate from Gold Canyon near Little Tujunga, officials said. Conflicting reports said the group wanted to stay, or be rescued, after firefighters lit backfires to fight the blaze in the area. Sheriff deputies returned to the area three times, officials said, but it appeared the group was not leaving.

As billows of white and black smoke danced ominously close in the Sunland-Tujunga area, Chuck Horn ushered his family and his two prized collectors' automobiles away from his home.

"We took pictures, tax returns, insurance forms, the dog, the chicken, and that's it," Horn, 61, a retired Los Angeles County public works employee, said as he prepared to drive away in his baby blue 1931 Plymouth three-window coupe. Next, he planned to move away a black 1911 Buick Model 33.

Sallie Lynne heard from a neighbor that her home near Acton had burned down. She waited yesterday at a roadblock just a few miles away, hoping to find out what happened to the animals she left behind: one blind cow, two baby cows, 20 sheep and 50 chickens.

"We just want to go up there and see how bad it is," she said.

Another fire in San Bernardino County was spreading out of control and threatening 2,000 homes in the apple-growing community of Oak Glen, near Yucaipa.

With fire raging down the mountainsides yesterday, the phone at Oak Glen's Los Rios Ranch rang so much that manager Devon Riley changed the number on his answering machine.

"I had three ladies on the phone in tears," he said. "They said they heard the apple orchards had burned up."

Despite the flames getting perilously close at times, the apples that made this town famous have escaped unscathed.

A second fire started in Yucaipa around 4:30 p.m. and was growing, with evacuations ordered for hundreds of homes in the Wildwood Canyon area. It was under air assault yesterday evening with aircraft that included a DC-10 tanker.