CHICAGO, United States (AFP) — Racial tensions soared in two US cities yesterday after three white men opened fire on a Black Lives Matter protest in Minneapolis and a Chicago police officer was charged with murder for shooting a black teen.

Five people were wounded, though none gravely, when the gunmen opened fire Monday night at the Minneapolis protest, police said.

Black Lives Matter Minneapolis vowed to continue its daily demonstrations protesting the fatal police shooting of Jamar Clark, 24, who they said was handcuffed when he was shot in the head on November 15.

“White supremacists attacked the _#_4thPrecinctShutDown in an act of domestic terrorism,”the group wrote on its Facebook page. “We won’t be intimidated.”

Meanwhile, the mayor of Chicago called for calm ahead of the release of a “hideous”video showing officer Jason Van Dyke fire 16 bullets into Laquan McDonald, 17.

A judge ordered the Chicago police dashcam video released to the public no later than Wednesday.

Van Dyke was charged with first-degree murder yesterday, the Chicago Tribune reported.

It will be the first time a Chicago police officer has been charged with first-degree murder for an on-duty fatality in more than 30 years, the newspaper said.

“We trust police officers to provide safety, build trust and uphold the law. If you violate that you’re going to be held accountable,”Mayor Rahm Emanuel told reporters Monday.

“This is a violation of your conscience and it is wrong and it is hideous.”

Emanuel spoke with community leaders and urged them to remind residents to express their right to protest in a “responsible, focused, peaceful way so your voices and your ideas are heard.”

The city approved a $5 million settlement for McDonald’s family in April and federal authorities have said they are investigating the case.

His family has said they do not want the video released because it will be too painful to see it played over and over again on the news.

“My nephew is shot in the back and all of those other places 16 times. Even when he was on the ground, the officer was still shooting him,”McDonald’s uncle, Shyrell Johnson, told WGN-TV last week.

Police have said McDonald was high on PCP, acting erratically and lunged at the officers with a knife.

“Despite the graphic nature of the video, we’re confident that my client’s actions were not only lawful, but also within department policy and within his training,”Van Dyke’s attorney, Daniel Herbert, told reporters last week.

“He was in fear for his life.”

Van Dyke, who has been on desk duty since the October 2014 shooting, did not speak to reporters when he arrived at the Chicago courthouse Tuesday morning.

In Minneapolis, police have said Clark died in a struggle with police who were responding to a domestic disturbance.

Minneapolis police said they were “actively investigating the shootings”and that additional uniformed officers had been called to the area.