From Quillette:

This pattern of events is familiar because it has repeated itself numerous times over American history following acts of police brutality, especially in cases where, as with Floyd, the victim was black. First, large numbers of people protest peacefully, drawing attention to their cause and attracting national sympathy. Then, a smaller group turns violent, causing destruction in the community and sometimes harming innocent people. That smaller group sometimes includes people who exploit the chaos for their own ends. During the Baltimore riots of 2015, for instance, the looting of pharmacies led to opioids and other drugs flooding the market, likely feeding drug dependency, enriching gangs, and fueling more crime.