ROHNERT PARK (CBS) — The National Weather Service has issued a flash flood warning for Sonoma County.

The warning was issued Saturday afternoon because flooding was either occurring or imminent and was in effect until 7:30 p.m.

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The warning covers the western part of the Laguna de Santa Rosa and western Rohnert Park, as well as the Petaluma area, particularly around Penngrove Park.

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Runoff from heavy rainfall will cause flooding of small streams and creeks as well as roadways, underpasses and other low lying spots.

Residents should not attempt to cross swiftly flowing water. The should turn around or risk drowning because the waters can rise rapidly.

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If flash flooding is observed, act quickly, and move to higher ground to escape flood waters. Do not stay in areas subject to flooding when water begins to rise.