Charleston's mayor said that the act of 21-year-old Dylann Roof to kill nine people in an African-American church was an act of "pure, pure concentrated evil".

The nine people, who lost their lives after Roof allegedly pulled his pistol and opened fire, include a state senator who doubled as the church's minister; three other pastors; a regional library manager; a high school coach and speech therapist; a government administrator; a college enrollment counselor; and a recent college graduate.

Roof said blacks were trying to become rulers and something was needed to be done to ensure protection of the white race. Roof was arrested on Thursday for allegedly committing the atrocity.

"Of all cities, in Charleston, to have a horrible hateful person go into the church and kill people there to pray and worship with each other is something that is beyond any comprehension and is not explained", said Mayor Joseph P. Riley Jr. He added that they are going to put their arms around that church and that church family.

It was seen in the surveillance video that the gunman entered the church Wednesday night. Charleston County Coroner Rae Wilson said that he did not appear threatening.

She said the group accepted him thinking he wanted to join them in this Bible study. He all of a sudden became aggressive and violent, she added.

Roof told his horrified victims that African-Americans were raping their women. President Barack Obama said on Thursday that the attack on black churches is not something new and threats are posed to the democracy and their ideals by hatred across races and faiths.