Wet roadways are believed to have contributed to numerous multi-car crashes around Sonoma County during the Thursday morning commute as rain returned to the area, the CHP said.

No serious injuries were reported, but at various times emergency crews and law enforcement were battling on several fronts at once.

Around 8 a.m., a five-car crash on eastbound Highway 12 in Santa Rosa blocked all eastbound traffic and "was the start of the whole 101/12 corridor area falling apart," Officer Steve Fricke said.

Within minutes, a multi-vehicle crash snarled traffic on southbound Highway 101 between Highway 12 and downtown, while a northbound car became disabled on the freeway near Todd Road, Fricke said.

Less than one hour later, two multi-car crashes occurred on Highway 101 in Santa Rosa and on the south side of Petaluma, the CHP said.

After weeks without rain, Fricke said, local roadways would have accumulated layers of oil, dirt and debris turned slippery by overnight rain, requiring motorists to adjust to changed conditions.

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