President Barack Obama went behind bars as he extended his campaign for reform in the criminal justice system, becoming the first sitting president to see inside a federal prison, NBC News reported. The president visited the sprawling El Reno Federal Correctional Institution in Oklahoma, a complex which includes sections of buildings separated by large green yards and barbed wire fences. While there, he met with six inmates in prison for drug offenses. "Every single one of them emphasized the fact that they had done something wrong, they are prepared to take responsibility for it, but they also urged us to think about how society could've reached them earlier on in life to keep them out of trouble," the president said. On Monday, the president commuted the federal prison sentences of 46 nonviolent drug offenders, 14 of whom were serving life terms. And on Tuesday, Obama argued for shortening or eliminating mandatory minimum sentences for those same offenders in a speech to the NAACP in Philadelphia.