ALTADENA, California - As Los Angeles construction worker Ivan De La Torre surveyed a landscape of smoking wreckage in fire-ravaged Altadena, a question nagged at him: how would insurance companies cover the cost of rebuilding an entire neighborhood?

As hundreds of Los Angeles residents return to find homes reduced to ashes due to a devastating wave of wildfires, many are fearful that their insurance policies may not cover the rebuild cost and that future premiums will be astronomical.

"My concern is that the insurance companies won't be able to handle all the claims and file for bankruptcy and that's that. It's scary," said De La Torre, 32, whose uncle and sister both lost their houses in a fire that consumed half of Altadena, a suburb north of Los Angeles of some 40,000 people.

Leo Frank III, a 66-year-old actor who lost his family home in Altadena, said he fears insurers could drag their feet on paying claims and fail to cover the full cost of reconstruction.

"We will rebuild. No one is taking our house," said Frank, as he hunted for a shower seat for his 96-year-old mother in a parking lot full of donated supplies in Pasadena.

"But it will be a mess."

Frank said he knows some neighbors who lost their homeowners coverage prior to the fires as insurers retreated from parched regions in California increasingly prone to wildfires.

"We were lucky we still had a policy," he said.

The wildfires, among the worst natural disasters ever to hit California, have killed at least 11 people and destroyed or badly damaged more than 10,000 structures.

Reuters contacted nine of the top home insurance companies in California for comment.

State Farm, Nationwide, Allstate, Mercury, Liberty Mutual and Farmers responded with statements saying they were working with policyholders to help them make claims, without addressing specific concerns about residents not receiving sufficient payouts or rising future premiums.

Following the fires this week, California Insurance Commissioner Ricardo Lara invoked moratorium powers to suspend all policy non-renewals and cancellations from insurance companies for one year.

Lara said in a statement on Friday that next week he will host free insurance workshops in Santa Monica and Pasadena, suburbs close to the two biggest fires.

U.S. insurance stocks slid on Friday as analysts estimated the insurance costs from the wildfire could top $20 billion. Private forecaster AccuWeather estimated the damage and economic loss from the fires at $135 billion to $150 billi...