20-year-old Clyde Township woman was seriously injured after she ran her car off North River Road and into a tree west of Timberline Drive about shortly after 3:00 p.m. Saturday in Clyde Township. St. Clair County Sheriff office reports that the woman was taken to Port Huron Hospital and then taken by air ambulance to another hospital after sustaining head injuries. The woman was going north on North River Road before the crash. Witnesses said her car was weaving before the crash. St. Clair County Sheriff Department is investigating the crash.