Brews there are a lot of images of Proud Boys and other Neo-Nazi member participating in the looting this weekend as well that are easy to find on Twitter. My best guess is that a wide range of opportunists showed up to spread chaos and steal things this weekend.
On a positive note, this is the best way that I've found to donate some money to the cause.
https://secure.actblue.com/donate/ab_mn
Split a donation to all groups listed on this page, or allocate specific amounts to individual groups:
Black Lives Matter Global Network
Reclaim the Block
National Bail Out
Black Visions Collective
NAACP Legal Defense and Educational Fund
The National Police Accountability Project
Color of Change Education Fund
Unicorn Riot
Campaign Zero
Advancement Project
The Marshall Project