A police car with broken windows is seen in a photograph released by the Milwaukee Police Department after disturbances following the police shooting of a man in Milwaukee, Wisconsin, U.S. August 13, 2016. Milwaukee Police/Handout via REUTERS

Protesters fired gunshots, hurled bricks and set a gas station on fire in the U.S. mid-western city of Milwaukee on Saturday night, hours after a patrol officer shot and killed an armed suspect who took flight after a traffic stop, authorities said.

The 23-year-old suspect, who had a lengthy arrest record, was carrying a stolen handgun loaded with 23 rounds of ammunition when police pulled over the vehicle for unspecified “suspicious activity,” authorities said. A second suspect who fled from the vehicle was quickly taken into custody.

A statement by the Milwaukee Police Department did not say whether the suspect who was killed had fired any shots or pointed the weapon at officers during the incident. Authorities did not disclose the race or the name of the suspect or the uniformed officer.

Later, a crowd of more than 100 people in the predominately African-American section of the city where the shooting occurred hurled rocks as police officers in riot gear attempted to disperse the protesters.

Authorities said gunshots were fired during the disturbance. The windows of at least two squad cars were smashed, and one officer sitting inside one of the vehicles was hit in the head with a brick.

Protesters set a police car ablaze and fires broke out at gas station, an auto parts store and at least three other businesses, officials and local media reported.

“Our city is in turmoil tonight,” said Alderman Ashanti Hamilton, president of the Milwaukee Common Council.

Mayor Tom Barrett appealed for calm.

“This is a neighborhood that has been unfortunately affected by violence in the recent past,” Barrett said, referring to a smaller disturbance a month earlier. “There are a lot of really, really good people who live in this area … and can’t stand this violence.”

But Alderman Khalif Rainey, who represents the neighborhood where the shooting and riots occurred, said the violence is a result of a long-term, systemic oppression of African Americans that has turned downtown Milwaukee into a “powder keg.”

“This entire community has sat back and witnessed how Milwaukee, Wisconsin, has become the worst place to live for African-Americans in the entire country,” Rainey said. “Now this is a warning cry. Where do we go from here? Where do we go as a community from here?

“Do we continue – continue with the inequities, the injustice, the unemployment, the under-education, that creates these byproducts that we see this evening? The black people of Milwaukee are tired. They’re tired of living under this oppression. This is their existence. This is their life. This is the life of their children.

“Now what has happened tonight may have not been right; I’m not justifying that. But no one can deny the fact that there’s problems, racial problems, here in Milwaukee, Wisconsin, that have to be closely, not examined, but rectified. Rectify this immediately. Because if you don’t, this vision of downtown, all of that, you’re one day away. You’re one day away.”

In the hours after the police shooting, which took place at about 3:30 pm, about 100 – 200 people gathered near the site of the shooting at N. 44th St. and W. Auer Ave. The crowd pushed against police in riot gear, eventually banging on police car windows, according to media reports.

Police say one officer was injured when a brick was thrown through the window of his squad car.

The unrest follows peaceful protests and some violence in U.S. cities over the past two years following high-profile killings by law enforcement officers in Baltimore, New York and Ferguson, Missouri.

Outrage over police violence toward minority groups has given rise to the Black Lives Matter movement and touched off a national debate over the race issue and policing in the United States.

As of 1 a.m. Central time, police said three arrests had been made in connection with the unrest.

Shortly after 2 a.m. police said they were restoring order to the area and reducing deployments, but local news footage also showed a liquor store in flames just minutes before the release of the statement.

The officer involved in the shooting is 24 years old and a six-year veteran of the force, police said. He was placed on administrative duty until an investigation and subsequent review by the Milwaukee County District Attorney’s Office is complete, a standard practice after shootings by law enforcement officers.

Madison365 staff contributed to this report from Reuters News.