A series of small grass fires along Highway 99 kept Modesto firefighters busy early Wednesday morning.
Seven fires, from 100 to 500 feet apart between Kansas and Woodland avenues, burned along the northbound lanes about 6:15 a.m., and all were knocked down in about 45 minutes, according to Battalion Chief Dan Hinshaw.
Nobody was injured and there was no damage reported although a couple of structures on Graphics Drive were threatened, Hinshaw said.
Hinshaw said one of the difficulties in battling the small blazes were choreographing the use of five engines at various spots, some coming from the north and others the south.
He said the 15 firefighters were helped by the cool early morning winds from the Sacramento-San Joaquin Delta, and the fact that state Department of Transportation crews had recently mowed the dry grass near the freeway.
Investigators were still trying to determine the cause of the fires.
Hinshaw said he doubted it was arson.
"It's pretty easy to start a fire along a freeway, but seven separate fires in a half-mile or quarter-mile stretch?" he said. "Somebody would have seen that and reported that."
He said one example of how separate fires like this can start is when a hot retread comes off a truck at a high speed and rolls along the grass, starting fires at various points along the way.