A police station in Minneapolis has been set alight during the third night of protests over the death of an unarmed black man in custody on Monday.
A police officer was filmed kneeling on the neck of George Floyd, 46, despite him saying he could not breathe.
US President Donald Trump said “thugs” were dishonouring his memory and called on the National Guard to restore order.
There have been demonstrations in other US cities such as New York, Denver, Phoenix, Chicago, Los Angels and Memphis.
In the past days, buildings have been burned to the ground or looted. On Thursday night protesters gathered outside the police department on 3rd Precinct, the epicentre of the unrest. Officers fired tear gas and rubber bullets trying to disperse the crowd. But the cordon around the police station, which is near where Floyd died, was breached by protesters, who set fire to it and two other nearby buildings as the officers withdrew.