It happened about 12:50 p.m. in an area about a mile south of Lighthouse Park, Mukilteo Assistant Fire Chief Brian McMahan said.
"She was sitting on a log and the log rolled, and she got her leg caught between the log and a rock," he said.
It took emergency crews about 30 minutes to find the woman and reach her, he said. She was in an area often covered by higher tides. It was between the shoreline and the railroad tracks and down an embankment. Emergency dispatchers were given limited information about the exact location.
The railroad tracks were temporarily closed during the rescue operation.
Passersby had helped move the log off the woman's leg when crews arrived.
Snohomish County Fire District 1's rescue boat got the woman on board and took her to an ambulance waiting at the Mukilteo dock, McMahan said.
She was taken to a local hospital with possible broken bones.
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