Categories Articles Days Before the Columbine Shooting’s 20th Anniversary, a ‘Credible Threat’ Puts Denver Schools in Lockout Post author By crystalg Post date April 16, 2019 TIME Tags 'Credible', 20th, Anniversary, Before, Columbine, Days, Denver, Lockout, puts, schools, shootings, threat ← What the Notre-Dame Fire Reveals About the Soul of France → Google takes a tiny step toward fixing AMP’s URL problem