Clashes and violence were, particularly in Minneapolis and Portland, initiated by protestors, counterprotesters, opportunistic criminals and by extremist groups. Various groups, including white supremacist and anti-government far-right groups, including the Proud Boys, were present at the protests in Portland.
Additionally, there were multiple reports, including videos, of overly aggressive police using excessive physical force on protestors. Police used violent tactics like tear gas, pepper spray and rubber bullets on innocent bystanders and journalists, often without any provocation. Some news agencies reported that the police aggression, meant to impose order, were instead inflaming tensions. Amnesty International denounced police violence against protestors and called for the police to stop their excessive militarized responses to the protests.
The murder of George Floyd set off protests in 60 countries, not only in the U.S. Unfortunately, police brutality is not uncommon around the world. If anything good came out of the murder of George Floyd and subsequent protests, no black man or woman has been killed by a rogue policeman in nearly five years. That we know of, anyway.