As I said on Tumblr, white people must not attempt to deny the racism of that action. White people must not scapegoat people with mental illness and refuse to take a good hard look at the culture that bred that hatred in the shooter. The Charleston massacre was not about mental illness, it was about racism and white supremacy.
Additionally, I would strongly recommend that anyone with the resources to do so donate to the families of victims and to the survivors, so that they do not have injustice compounded upon atrocity, and do not have that horrible crime ruin their finances in addition to hurting them, traumatizing them, and/or killing their loved ones.
Beyond that, this is not a time for me to be talking. Have some links to stuff written by people who should be talking at this time:
A final point: If any black person wants me to signal boost anything right now or wants to use this blog as a platform in any way: leave a comment or get in touch by email (my email is ischemgeek AT gmail DOT com).