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 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.

In the second season finale, college students get trapped when stacks of logs collapse during the construction of a massive bonfire at Texas A&M University.