Witnesses are needed after a pedestrian-involved collision sent an elderly woman to Newmarket hospital. First responders rushed to Yonge St. at Bristol Rd. around 2:00 Monday afternoon, with reports a pedestrian had been struck by a vehicle. An 87-year-old woman from Holland Landing is in hospital with life-threatening injuries, while the 36-year-old driver of the vehicle was not hurt. Contact the York Regional Police Service if you were witness to the crash.