A tornado hits an elementary school in Oklahoma, and a teacher whose class was impacted shares her harrowing story in the second-season opener.

A gunman holds a maternity ward hostage, seeking the doctor who performed a tubal ligation surgery on his wife two years earlier.

A marathoner falls in a canyon and breaks her pelvis while out on a training run with her dog, and the faithful canine searches for someone to rescue its injured owner.

A nurse is abducted from her apartment by a man who forces her into his car and robs an auto-parts shop.

A car gets hit by a truck and dangles over a guardrail on a California highway, and rescuers try to save a mother and two daughters trapped inside.