San Diego

Arson was blamed for the fast-moving, 4,500-acre brush fire that swept through the Black Mountain area last Tuesday, a Fire Department spokesman said.

Fire investigators who combed the area Thursday determined that a separate, 5-acre fire broke out before the larger blaze started a mile away. That led officials to believe that both fires were set.

The odds that two accidental fires started in the same location are too great, John Buono, a fire investigator, said.

“We are waiting for someone to call in with information, saying they did it or know someone who did,” Buono said.

Arsonists usually set fires to get attention, Buono said, and are caught when they start telling people about starting one. “It’s like saying, ‘I want attention.’ Someone as a sign of power would say, ‘I was responsible. I did all that,’ ” he said.

Fire raged through the Black Mountain area again Sunday when 200 acres burned in the North City West south of Tuesday’ fire.

This time a new housing development at the foot of Shaw Ridge Road was threatened by flames, forcing its residents to flee, a fire official said.

Strong Santa Ana winds helped rekindle last week’s blaze that took more than a day to combat.

The weekend fire took 150 firefighters seven hours to fully contain, Fire Department spokesman Jon MacDonald said. No injuries or damage were reported, and residents were allowed back into their after a few hours, MacDonald said.