Firefighters stopped the forward progress of the Little Fire near Pleasanton late Tuesday after it burned about 1,000 acres, though evacuation orders remained in effect and crews continued working in rugged terrain to gain full control.
Regional strike teams and aircraft were assigned to the fire, Alameda County Fire spokesperson Cheryl Hurd said. Some resources were expected to be released as conditions stabilized.
"The forward progress of the head of the fire has stopped, but all agencies are working in rugged terrain to get full control of the fire," Hurd said.
Cal Fire was leading the response, with the Alameda County Fire Department and other regional agencies assisting, Hurd said.
The blaze which started near Vallecitos and Little Valley roads in rural southeastern Alameda County was about 10% contained, according to Cal Fire.
Firefighters were contending with limited access and hot weather as they attacked the blaze from the ground with engines, crews and bulldozers and from the air with tankers and helicopters. Cal Fire's Santa Clara Unit and the Alameda County Fire Department were operating under unified command.
Additional resources were arriving from neighboring Contra Costa County, including a battalion chief and five engines, according to ConFire.
One firefighter was injured during the response, according to Cal Fire. The agency did not immediately release details about the injury or the firefighter's condition.
Evacuation orders covering areas near Pleasanton, Livermore and Sunol remained in effect Tuesday night. Alameda County warned of a "serious threat to life and property" and ordered people in the affected areas to leave immediately.
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The evacuation area encompassed roughly 4,900 residents, according to an estimate displayed on the Genasys evacuation map. It was not clear on Tuesday evening how many people had left their homes.
Evacuees were directed to use Highway 84, also known as Vallecitos Road, or Happy Valley Road. A temporary shelter opened at the Pleasanton Senior Center, 5353 Sunol Blvd.
The fire's cause remained under investigation. PG&E said there were no outages in the fire area and that the blaze had not affected its equipment.
"The fire is under investigation, and it has not impacted our assets at this time," PG&E spokesperson Tamar Sarkissian said.
Residents were told to not return until authorities lifted the evacuation orders. Alameda County also urged people, when safe, to check on neighbors who might not have received the alert or who could need help leaving.
In the Avignon neighborhood, Harmit S. Toor said he was gathering essential belongings after his family's home was placed under an evacuation order.
"I am in the middle of evacuating," Toor said. "We're just trying to be as prepared as possible."
Toor said he, his wife and their two sons were taking passports, important documents and other possessions that would be difficult to replace. They planned to stay with his brother-in-law in the Hayward hills.
As they prepared to leave, Toor said he could see smoke and helicopters flying over his home.
ConFire said the wind-driven blaze was advancing toward the Ruby Hill neighborhood, where about 800 homes surround a golf course.
The evacuation orders also affected rural properties where residents and workers were trying to protect livestock.
Renee Turnbull, 64, rushed to Van Dyke Ranch after learning that the fire had started near the Little Valley Road property where her three horses are boarded.
Turnbull said she saw flames burning across the Koopman and Van Dyke ranches and along a fence line bordering a former power plant property, extending to the top of a hill.
Her horses were safe on the opposite side of the ranch, she said, but she had prepared another option if the fire crept closer.
"If I couldn't get them out with the trailer, I was going to ride one and pony the other two across properties," Turnbull said.
Staff at the Club at Ruby Hill was evacuating golfers, restaurant patrons and employees as sheriff's deputies arrived Tuesday afternoon.
"We're just closing down the golf course, the restaurant, all outlets - clearing people from the course and doing the thing," Marcy Davisson, the club's head of food and beverage, said by phone.
During the call, people could be heard urging others to "Be safe!" and asking, "All the kids are gone?" as employees hurried to put away lawn games and clear the property.
Pleasanton activated its emergency operations center as the fire expanded, City Council Member Julie Testa said.
Testa said she could hear sirens from her home and see smoke in the distance.
"It's not as close to my home as I thought," she said.
The fire began shortly before 3 p.m. and grew rapidly as it moved through grass.
The blaze produced a large plume that was visible from Oakland and other communities across the Bay Area. Satellite data indicated that the smoke rose as high as about 7,000 feet.
No injuries or structural damage had been reported as of Tuesday evening.
The fire broke out as temperatures across the inland Bay Area climbed into the 90s. The National Weather Service issued a heat advisory through 9 p.m. for much of the region, with temperatures expected to reach the mid-90s to low 100s.
Humidity was expected to rise Tuesday evening, potentially improving firefighting conditions, though breezy weather was forecast to continue.
Anthony Edwards, Sarah Ravani and Jessica Christian contributed to this report.
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