The protesters raged through the night, invoking the name of George Floyd, a black man who died after a white police officer knelt on his neck for several minutes even after Floyd stopped moving and pleading for air.

Some held up signs with Floyd’s last words: “I can’t breathe.” Graffiti on city walls called police murderers. In a highly symbolic image, a protester carried a U.S. flag upside down, a sign of distress.

Among Thursday night’s casualties was a Minneapolis police station that demonstrators torched after the department abandoned it. Some protesters doused their faces with milk after being exposed to tear gas from police. Others set off fireworks as fires burned in the background. Looting was rampant.

It was the third night of violent protests after Floyd died in a confrontation with officers outside a grocery store.

Fires continued to burn Friday morning in Minneapolis and nearby St. Paul, and National Guard members were being stationed in locations to help stem looting.

Under fire from President Donald Trump, who criticized the city’s mostly hands-off approach with protesters, Minneapolis Mayor Jacob Frey defended the policy and said it was his decision to evacuate the police precinct because officers were at risk.