The mayor of Milwaukee in Wisconsin has imposed a curfew on the city amid the ongoing protests against police brutality.
Mayor Tom Barrett imposed the curfew at 10 pm on Monday, urging young people to stay indoors.
"After 10 o'clock your teenagers better be home or in a place where they're off the streets," Barrett said.
"This is not the place where you go to gawk, it is not the place where you go to take pictures, it is not the place to drive your car around," he added.
The violence erupted after African American Sylville K. Smith, 23, was killed by an officer on Saturday, when he fled a traffic stop on foot.
The protests continued for the second night on Sunday which prompted Wisconsin Governor Scott Walker to put the National Guard on alert.
The unrest peaked when a BP gas station was set on fire and gunshots prevented firefighters from doing their job.
Debris was thrown at police officers as they attempted to disperse protesters and gunshots were heard.
An 18-year-old man was shot and injured and seven cops were wounded after protesters pelted them with rocks and bricks, according to Milwaukee Police Chief Ed Flynn.
At least seven police cars sustained heavy damage as a result of the violence.
Police have arrested eleven men and three women, who were charged with disorderly conduct, Flynn said.
The incident comes amid renewed anger over the fatal shootings of several young African Americans by police around the US in recent weeks.