Armed police transport a man to a hospital after getting injured during unrest in Milwaukee, Aug. 14, 2016.
Armed police transport a man to a hospital after getting injured during unrest in Milwaukee, Aug. 14, 2016.

The Midwestern U.S. city of Milwaukee, Wisconsin, saw a second night of unrest Sunday into early Monday, with police in riot gear confronting a group of people protesting the killing of a black man by police.

The Milwaukee Police Department said that an 18-year-old man was shot during the protests and they used an armored vehicle to take him to a hospital.  But there was no repeat of the widespread destruction of property that occurred Saturday, when at least six businesses were torched and destroyed.

Officers ordered people to disperse Sunday and reported having rocks and other objects thrown at them, with four law enforcement personnel injured.  The department also said 14 people were arrested.

WATCH: Police Chief Edward Flynn on casualties

Similar protests erupted Saturday night after an officer shot 23-year-old Sylville Smith in the chest and arm after pulling over his car for what authorities described as suspicious behavior.

Flynn told reporters Sunday that Smith ran several meters from his car before the officer, who is also black, fired his gun. The chief said Smith was armed with a gun and pointed it at the officer.

"It was in his hand. He was raising up with it," Flynn said.

Milwaukee Mayor Tom Barrett said that the officer was wearing a body camera during the altercation and that the video will be made public "at the appropriate time." Barrett said a still image from the video "demonstrates, without question, that he had a gun in his hand.  And I want our community to know that."

Authorities respond near a burning gas station as
Authorities respond near a burning gas station as dozens of people protest following the fatal shooting of a man in Milwaukee, Aug. 13, 2016.

Wisconsin Governor Scott Walker activated about 125 members of the state's National Guard and placed them on standby in case of further violence, but they were not called in to help Milwaukee police.

Smith's sister, Kimberly Neal, told The Associated Press the family wants prosecutors to file charges against the officer.

Milwaukee's police department was also the subject of protests in 2014 after an officer killed a mentally ill, unarmed black man.  Last December, the U.S. Justice Department announced it was conducting a review of the department. The probe's listed objectives include assessing efforts to recruit officers representative of the Milwaukee community, use of force practices, and how officers are trained in conducting traffic stops.

Milwaukee is a city of about 600,000 people. Nearly 40 percent of them African-Americans, who are heavily concentrated on the north side.

Smith's shooting happened in the Sherman Park neighborhood, which is in north Milwaukee. Residents there say the city has been unresponsive to their needs.

Alderman Khalif Rainey, who represents Sherman Park, says Milwaukee's black residents are "tired of living under this oppression."

He said he does not condone violence, "but nobody can deny that there are racial problems here in Milwaukee, Wisconsin, that have to be rectified.''