LOS ANGELES — A group of college students who lit a ridge-top bonfire is being blamed for accidentally sparking one of three ferocious wildfires that collectively destroyed about 1,000 homes and blacked more than 65 square miles.

An anonymous tipster told police 10 students gathered a week ago near an abandoned home in the hills of Montecito, Santa Barbara County Sheriff Bill Brown said Tuesday.

They built a bonfire during the night and stayed until 3 a.m. to 5 a.m. Thursday morning. By Thursday night, when winds took hold of it, the seemingly harmless blaze was on its way to destroying 210 Santa Barbara homes, including multimillion-dollar properties, authorities said.

The students, aged between 18 and 22, apparently believed they had put out the fire before leaving. Fire officials said it is not uncommon for such fires to have the potential to re-ignite days later.

“It appears this fire was the result of carelessness, not criminal intent,” said Brown, who added that the students all lived locally and attended the same school. He declined to say which one or identify the students.

Though Brown said there was no “malicious intent,” the county district attorney will review the case and determine if criminal charges are filed.

The fire burned intensely into the weekend, chewing up 1,900 acres and injuring more than two dozen people, including a Montecito couple who remained in critical condition Tuesday. Lance and Carla Hoffman, both 29, were severely burned while fleeing their home, which was destroyed.

The Montecito blaze was the first of three to erupt in Southern California that collectively damaged or destroyed about 1,000 homes.

In Los Angeles County, an 11,234-acre fire in the San Fernando Valley was 85 percent contained this morning. About 50 miles to the south, the last remaining evacuation order was lifted in Orange County, where a nearly 29,000-acre complex of fires was 90 percent contained and some of the 3,760 firefighters were being sent home.

The worst-hit area was the Oakridge Mobile Home Park in Sylmar, about 20 miles north of downtown Los Angeles, where 484 homes were destroyed. For a second day residents were allowed back in to salvage what they could from acres of ashes.

Los Angeles County officials sent crisis counseling teams to comfort the victims.

Meanwhile, lawmakers geared up to help those who lost their homes. President George W. Bush made a disaster declaration for California, freeing up federal aid to areas ravaged by the wildfires that blackened more than 65 square miles.

Gov. Arnold Schwarzenegger signed an executive order waiving state fees for fire victims who need to replace destroyed birth certificates and other documents or obtain state property inspections. The order also waived a one-week waiting period for unemployment insurance applicants who lost their jobs because of the fire.

The state has spent $305 million on emergency firefighting since the start of the fiscal year on July 1, $236 million more than lawmakers had allocated in their 2008-09 spending plan.

That budget, which the governor signed in September, also included a $1.7 billion reserve for this fiscal year, some of which could have been used to help pay extraordinary firefighting costs.