Last Updated Nov 24, 2015 10:00 AM EST
MINNEAPOLIS -- Five people were shot Tuesday night near the site of an ongoing protest organized by the Black Lives Matter movement over the fatal shooting of a black man by a police officer, police here said.
Later, the brother of the police shooting victim called for the protest to end, citing Tuesday's shooting.
CBS Minnesota reports the five people shot Tuesday were hospitalized with non-life threatening injuries.
Mica Grimm, an organizer with Black Lives Matter who said she arrived on the scene soon after the shooting, told The Associated Press two of the wounded were hit in the leg, another in the arm and a fourth in the stomach.
"Everyone has been on high alert because in the last several days there have been lots of conversations of white supremacists' websites and chatrooms, where they talked about coming to the protests," Minneapolis NAACP president Nekima Levy-Pounds said. "They talked about having weapons and also doing things that would agitate the crowd and incite confrontation between police officers and protesters."
The Star Tribune reported the shootings occurred near an alley about a block away from the 4th Precinct stationhouse, where protesters have been conducting a sit-in since the shooting of 24-year-old Jamar Clark on Nov. 15.
Witnesses at the scene claimed to CBS Minnesota that the shooters were white supremacists and were hanging around the rally. Protesters say they asked the alleged white supremacists -- all of whom were reportedly wearing masks, to leave, but the men came back a short time later and fired six shots at the crowd.
A crowd gathered at the scene after the shooting, and heated words were exchanged with responding officers.
Police said in a statement, "Dozens of officers responded almost immediately, attending to victims, and secured the scene. Additional resources were called in and are actively investigating the shootings, interviewing a multitude of witnesses. The Police Department is working to identify suspects. The police are asking that anyone with information to please come forward."
Clark's brother, Eddie Sutton, issued a statement late Tuesday saying, "Thank you to the community for the incredible support you have shown for our family in this difficult time. We appreciate Black Lives Matter for holding it down and keeping the protests peaceful. But in light of tonight's shootings, the family feels out of imminent concern for the safety of the occupiers, we must get the occupation of the 4th precinct ended and onto the next step."
The scene early Tuesday was quiet, with about 200 people milling around and talking. Campfires were lit for warmth amid freezing temperatures. One man with a bullhorn led protesters in chants of "Jamar Clark!"
Black Lives Matter had previously planned to announce "next steps" Tuesday morning following a weekend meeting with community members about strategy.
Authorities have said Clark, 24, was shot during a struggle with police after he interfered with paramedics who were trying to assist an assault victim. But some people who said they saw the shooting allege Clark was handcuffed.
Protesters, some from Black Lives Matter, and Clark's family have been calling for investigators to release video of the shooting. The state Bureau of Criminal Apprehension said it has video from the ambulance, a mobile police camera and other sources, but none shows the event in its entirety. The agency, which is conducting a state investigation, said releasing the footage now would taint its probe.
The protesters have been refusing to leave until the video is made public.
A federal criminal civil rights investigation is also underway to determine whether police intentionally violated Clark's civil rights through excessive force.