A Santa Rosa crash Wednesday morning involved a 90-year-old driver and a 27-year-old Santa Rosa motorcycle rider who lost a leg in the Bennett Valley Road collision, Santa Rosa police said.

Driver Elsie Dembowsky of Santa Rosa was starting a turn as rider Alan Richardson headed into the intersection of Holland Drive and Bennett Valley Road at 9:40 a.m., said Sgt. Rich Celli.

Who was at fault remained under investigation. Officers are still were looking at speed and who had the green light.

Both were travelling on Bennett Valley Road, heading toward each other, when Dembowsky began to turn onto Holland.

Richardson veered in an attempt to avoid the car, but clipped the Toyota Avalon and was thrown into a signal pole.

Dembowsky wasn't injured.

There were no skid marks at the scene. Officers have one witness to the crash and are hoping others will contact them.

Officers also will check Dembowsky's driving history. The crash occurred on her birthday.

As well as losing his left leg, Richardson suffered other life-threatening injuries and had a crushed pelvis and right leg. He was in surgery Wednesday afternoon.

Bennett Valley Road was closed for hours from Farmers Lane to Yulupa Avenue for the crash investigation.

Celli asked anyone with information to call Officer Steven Merical at (707) 543-3636.