The shooting at Centennial in Centennial began just after this morning Janitor Whitney Riley saw a student armed with a shotgun , running military-style . `` We were shaking . `` He goes 'Do what would you do in a lockdown drill . We were crying , '' ninth -grader Whitney Riley said . Fabian Llerenas and his classmate thought initially it was an explosion in a chemistry class .
The shooting at Centennial in Centennial began just after this morning Janitor Whitney Riley saw a student armed with a shotgun , running military-style . `` We were shaking . We were crying , '' ninth -grader Whitney Riley said . Fabian Llerenas and his classmate thought initially it was an explosion in a chemistry class .