Fire spreads up the north side of the San Jacinto Mountains, near wind turbines at the Silver Fire, near Banning, California August 8, 2013. [Photo/Agencies]

BEAUMONT, Calif. - A rapidly spreading wildfire chewed through a rugged Southern California mountain range on Thursday, destroying more than two dozen homes, threatening more than 500 other residences and forcing some 1,800 people to flee.

Six people were injured, while more than 1,400 firefighters and nine helicopters battled the flames as they pushed eastward along the San Jacinto Mountains, a desert range 90 miles east of Los Angeles, Cal Fire Riverside Chief John R. Hawkins said.

A man near the origin of the fire suffered serious burns, Hawkins said. Five firefighters were also injured, including two who suffered heat exhaustion. Officials did not have details to release on the other three.

After surveying badly charred areas, many of which burned amid the fire's out-of-control growth in the hours after it broke out, officials said 26 homes and one commercial building were destroyed and two other structures were damaged.

Hawkins said the wind-fed fire that sparked at 2:05 pm Wednesday is one of the "most rapidly spreading, dangerous fires that I've seen" in his 50 years as a firefighter.

The fire was estimated at nearly 22 square miles Thursday, with 20 percent containment, but it was growing, causing concern that the direction could change in the area, which is known as a wind tunnel.

"The conditions at the front right now are very dangerous," Hawkins said.

Authorities still have not determined what caused the fire.

Evacuation orders were issued in five towns. Flames were marching toward the hardscrabble town of Cabazon, where hundreds scrambled to leave in the pre-dawn hours Thursday as the mountain ridge behind their homes glowed red.

Many returned after sunrise to pack up more belongings and watch the flickering line of fire snaking along the brown, scrubby mountains.

Linda Walls, 62, sat with her family in lawn chairs and watched fire crews scrambling to douse the flames marching toward her modest home less than a quarter mile away. An American flag flapped in the gusty wind that kicked up the fire. She wiped her brow, feeling the scorching heat.

Gray and pink-tinted clouds billowed across the otherwise crystal blue sky. Neighbors could be heard coughing as they filled the beds of pickup trucks with motocross bikes, boxes of clothing, toys and packaged food.

"It seems to be taking off now," she said as sirens whirred by. "All you see are the firemen inside the blaze."

At the end of her street, a group of ostriches paced in their cages as the hill above them burned. A firefighter rushing by said they would do what they can to protect them. Nearby another pen was filled with goats.