The governor of Wisconsin has activated the National Guard after a night of violence that included the toppling of two statues.
Tony Evers made the move after protesters also threw a Molotov cocktail into a government building and a state senator said he was attacked.
One of the statues pulled down was of an anti-slavery US Civil War hero.
The violence from a group of between 200 and 300 people broke out on Tuesday night as crowds protested against the arrest of a black man who shouted at restaurant customers through a megaphone while carrying a baseball bat.
Officers used pepper spray to repel protesters who were trying to gain entry into the historic centre of state government, Madison police said.
After touring the damage on Wednesday, Mr Evers said: “What happened in Madison last night presented a stark contrast from the peaceful protests we have seen across our state in recent weeks, including significant damage to state property.”
The violence exposed simmering anger over the 2015 shooting by police of a 19-year-old black man by an officer who was eventually cleared and remains on the force. That shooting has been referenced by protesters in recent weeks.
The violence started after Madison police arrested a protester who came to a restaurant with a baseball bat on his shoulder. Video released by Madison police shows the man, Devenore Johnson, talking through a megaphone while walking around the restaurant’s outdoor patio. He walks inside and paces through the restaurant with the bat on his shoulder, saying he’s “disturbing” the restaurant before walking out.
On another video released by police, as many as five officers can be seen carrying Mr Johnson to a police car after he resisted arrest. Police said the man briefly escaped from the car before being tackled.
Mr Johnson was charged in 2015 with being a passenger in a stolen car, resisting an officer and theft, according to online court records. He pleaded guilty to being a passenger and was sentenced to probation. The following year he was charged with being a party to armed robbery and theft. Under a plea deal, he was sentenced to probation after pleading guilty to theft.
Police said a group of 200 to 300 people gathered and entered a private building where they surrounded a tow truck, forcing the driver to abandon it. The crowd broke windows in multiple buildings, threw a Molotov cocktail into the city-county building and brought down the statues.
"Everyone – police, protester, elected official, business owner, resident – everyone must find it within themselves to show compassion and kindness for each other, and to care about each other's safety and well-being." Mayoral statement on recent violence: https://t.co/e0cDsh55Vk
— City of Madison, Wisconsin (@CityofMadison) June 24, 2020
Protesters chanting for Mr Johnson’s release also broke glass at the Tommy Thompson Centre, named after the former Republican governor, and smashed windows and lights. Early on Wednesday, police in riot gear worked to clear a crowd of about 100 people that remained in the area.
One of the statues toppled, decapitated and dragged into a lake about half a mile away was of Civil War colonel Hans Christian Heg. He was an anti-slavery activist and leader of an anti-slave catcher militia in Wisconsin who fought for the Union and died from injuries suffered during the Battle of Chickamauga.
The base of the statue was defaced with graffiti that read “Fire Matt Kenny”, a reference to a white Madison police officer who shot and killed 19-year-old Tony Robinson, a black man, in 2015.
Mr Kenny said Mr Robinson had attacked him and he feared he would take his gun. Dane County District Attorney Ismael Ozanne, who is black, cleared Mr Kenny of any criminal wrongdoing and he remains a Madison officer.
The other statue taken down represents Wisconsin’s motto of “Forward”. The statue had been vandalised in past protests with paint thrown on it and graffiti spray-painted on and around it.
Democratic state senator Tim Carpenter was assaulted after recording a mobile phone video of protesters.
Mr Carpenter tweeted: “Punched/kicked in the head, neck, ribs. Maybe concussion, socked in left eye is little blurry, sore neck & ribs. 8-10 people attacked me. Innocent people are going to get killed. Capitol locked- stuck in office.Stop violence nowPlz!”