A man was charged with setting one of nearly a dozen fires that have destroyed homes and raced through nearly 20,000 acres of northern and eastern San Diego County brush land, but most of the blazes seemed to be dying down, despite the eruption of a new fire at the Camp Pendleton Marine base. "Thousands of firefighters and fleets of water-dropping military and civilian helicopters planned fresh battles Saturday. Investigators, meanwhile, continued to seek the causes of the conflagrations that burned at least eight homes and an 18-unit condominium complex, emptied neighborhoods and spread fields of flame, smoke and ash that dirtied the air in neighboring Orange County and as far north as Los Angeles County," Associated Press reported. Alberto Serrato, 57, pleaded not guilty Friday to an arson charge in connection with one of the smaller fires, a 105-acre fire in suburban Oceanside that started Wednesday and is fully contained, the report said. Tanya Sierra, a spokeswoman for the San Diego County district attorney's office, said witnesses saw Serrato adding dead brush onto smoldering bushes, which flamed up. "He has not been connected to any other fire," Sierra said.