NISSWA, Minn. – A Coon Rapids mother driving a snowmobile with her teen-age son on back were injured when the machine left the trail at a curve and struck a tree. Both were ejected. The son, age 16, was was airlifted 75 miles to a St. Cloud hospital with serious injuries. The mother, age 49, was transported 12 miles to the Brainerd hospital. This was shortly before 11:40 a.m.