Grundy County authorities continue to investigate an accident that claimed the lives of two Grundy Center high school students. The crash killed 18-year-old Austin Tjepkes and his 14-year-old sister, Whitney. Sheriff’s officials say the teens died when their car went through a stop sign in rural Grundy County and collided with a truck. The truck’s driver and his passenger escaped serious injury. The accident happened Monday morning while the teens were on their way to school. The deaths have left the community and the school in shock. A team of counselors are helping students and faculty members deal with the tragedy.