Police officers gave a black man multiple warnings to drop a handgun before one of the officers opened fire and killed him, Charlotte, North Carolina’s police chief said Wednesday, hours after protesters and police clashed in unrest that saw tractor-trailers looted and set on fire.

More than a dozen officers were injured, including one who was hit in the face with a rock. Authorities had to use tear gas to disperse the protests in North Carolina’s largest city, which joins Milwaukee, Baltimore and Ferguson, Missouri, on the list of U.S. cities that erupted in violence over the death of black men at the hands of police.

Charlotte-Mecklenburg Police Chief Kerr Putney said during a news conference that 43-year-old Keith Lamont Scott was shot because he was armed and posed a threat. But a woman who said she was Scott’s daughter posted a video on Facebook soon after the shooting, saying that

her father, who had an unspecified disability, was holding a book, not a gun.

The protest in Charlotte came hours after hundreds of people rallied outside Tulsa police headquarters, calling for the firing of police officer Betty Shelby, who shot 40-year-old Terence Crutcher on Friday during a confrontation in the middle of a road that was captured on police dashcam and helicopter video.

Shelby’s attorney has said Crutcher was not following the officers’ commands and that Shelby was concerned because he kept reaching for his pocket as if he were carrying a weapon. An attorney representing Crutcher’s family says Crutcher committed no crime and gave officers no reason to shoot him.

“These tragic incidents have once again left Americans with feelings of sorrow, anger and uncertainty,” U.S. Attorney General Loretta Lynch said at the International Bar Association Conference in Washington. “They have once again highlighted — in the most vivid and painful terms — the real divisions that still persist in this nation between law enforcement and communities of color.”