California fire officials said Sunday they are still looking for an elusive white Ford pickup that was seen in the area about the same time the Santigao fire, one of the largest of the blazes, started.

Orange County Fire Authority Battalion Chief Kris Concepcion told FOXNews.com there have been over 800 calls made into the arson tip line but none has led to any information about the Ford F150 model believed to be between the years of 1998-2004 with chrome tubular running boards.

"We're not considering the owner or operators of the vehicle suspects, merely they are just wanted in connection for details to help solve the crime."

A reward for information leading to the arrest and conviction of a suspect in what investigators believe was a deliberately set fire now stands at $250,000.

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Meanwhile, firefighters Sunday hoped to hold on to the strong gains they made against Southern California blazes, despite a forecast of warmer, drier weather and a continuing threat to some homes.

Firefighters say they're optimistic they can make more gains today against Southern California wildfires even though the weather will be hotter and drier.

Calmer winds and even a little drizzle yesterday helped crews tighten the noose on the major fires after a week of blazes that killed seven people, destroyed more than a half-million acres of land and burned nearly 1,800 homes.

Four fires in San Diego and San Bernardino counties are nearly fully contained.

However, more than 21,000 structures are still threatened and more than 15,000 firefighters are on the lines.

Several churches in fire areas will be holding Sunday services for fire victims. The congregation of a church in San Diego County will worship even though their church was gutted by fire.

The Associated Press Contributed to this report