20/20: In an Instant S02E01 - Tragedy in Tornado Alley

It was just after 1 p.m. on May 20, 2013 when the Storm Prediction Center issued a tornado watch for Eastern Oklahoma. Two hours later, storm spotters confirmed that an EF5 tornado had touched down and was ripping across the state towards the city of Moore, where school was in session.

As sirens blared, teachers at Plaza Towers Elementary donned brave faces while bracing the students for impact. Talking for the first time ever on television, teacher Jennifer Doan, whose Plaza Towers class was the hardest hit, shares her very personal story of tragedy and triumph left in the tornado's wake.