Sweetwater police Detective Juan Llera was at his office a few blocks away, when he heard what he thought was a bomb exploding. It was not a bomb; it was a bridge, a structure every American has passed under hundreds of times. But in an instant, this 950-ton span under construction at the Florida International University collapsed, and with no time to act or to flee, the cars that just so happened to be below it were pancaked under the rubble. Six people died.