Question: Who is "Kansas Mutual Aid", "Solidarity Center", and/or "ARISE"?

I'm from Connecticut and we just had a local young man charged with setting fire to a Bronx army recruiting office. Anywho-all the solidarity emails going around direct people to "Kansas Mutual Aid." And the only action is to send them money. Who are they? I can find no information on them. And the only references are the same: the address where to send money.