MADISON, Wis. — Hundreds of volunteers gathered early Sunday morning in downtown Madison to clean up after a night of violent protests over the death of George Floyd in which a police car was burned, businesses were broken into and a museum and other buildings were vandalized.

More than a thousand people held a peaceful protest Saturday afternoon in the Wisconsin capital, but like many of the protests around the country over the death of Floyd in Minneapolis, it later took a violent turn, with a group of about 150 demonstrators throwing rocks at police in riot gear who fired tear gas on the crowd.

Police said Sunday that 75 stores were damaged or broken into overnight and three people were arrested. One police officer was injured, but protective equipment prevented more serious injuries, acting Police Chief Victor Wahl said in a blog post.

One Madison police cruiser was broken into, driven a short distance and then set on fire, police said. Two rifles were stolen from the car, police said, noting that an armored police rescue vehicle was also hit by a bullet and multiple small fires were set and extinguished in the area.

Madison Mayor Satya Rhodes-Conway declared a state of emergency and imposed a 9:30 p.m. Sunday curfew in downtown Madison where the previous night's unrest occurred. Gov. Tony Evers authorized Madison authorities' request for help from the Wisconsin National Guard, and troops will be available Sunday, said his spokeswoman, Melissa Baldauff.

Most of the damage was to stores located near the state Capitol, but police said stores throughout the city, including at shopping malls several miles away, were also damaged.

Among the businesses that were targeted was the gift shop at the Madison Museum of Contemporary Art, where several protesters threw large chunks of concrete through the display window. A man who tried to stop them was knocked to the ground as protesters knocked items off the store shelves, the Wisconsin State Journal reported.

In Milwaukee, Mayor Tom Barrett said Sunday he is extending a citywide curfew a second night after protests following the deaths of Floyd in Minneapolis and a local man in an altercation with an off-duty Milwaukee police officer. The curfew goes from 9 p.m. Sunday until 7 a.m. Monday.

The Milwaukee Journal Sentinel reported 125 members of the Wisconsin National Guard will be on duty again Sunday night. “I think the National Guard did a wonderful job.” Barrett said.

Evers on Saturday called on the state National Guard to help support law enforcement in Milwaukee. A 38-year-old police officer suffered a minor gunshot wound early Saturday on Milwaukee’s south side where protesters had gathered near a police precinct. Milwaukee Police Chief Alfonso Morales said the officer is recovering at home and that no officers were hurt Saturday night.

Floyd, who was black and handcuffed, died Monday after a white Minneapolis police officer used his knee to pin Floyd to the ground for several minutes while Floyd pleaded for air and eventually stopped moving. The officer was charged with third-degree murder and manslaughter on Friday. He and the other three officers who were arresting Floyd were fired on Tuesday. None of the other officers have been charged.