https://www.gannett-cdn.com/presto/2019/04/19/PCIN/1a4421cc-b439-4b7d-a4b0-122e2b1d9270-cindc5bk-5iajaslj7co1dhhlrovn_original.jpg cincinnati.com today in history, april 20: columbine high school massacre 2019-04-20 Today History, April 20 years since Columbine High School massacre. ..…