Authorities said a man is currently in stable condition at the hospital after he was assaulted by people in Victory Park, Dallas, on Saturday in an incident that went viral on Twitter.
The incident unfolded amid hours of destruction, looting, and arson across the Texas city.
The man confronted protesters, who then assaulted him.
A video shot by Elijah Schaffer of Blaze TV showed a group of what appear to be protesters beating the man while he was on the ground. Witnesses then were seen attempting to tend to his injuries.
The man was taken to the hospital before police arrived on the scene, the report said.
Dallas Mayor Eric Johnson told reporters that he had seen portions of the video.
“It’s unacceptable for a beating to happen like that in my city,” he said. “The police are looking into that situation and that’s going to be addressed in our criminal justice system.”
Another night of outrage left stores looted and cars smoldering in many U.S. cities on Sunday as curfews failed to quell violence that replaced peaceful daytime demonstrations over the death of a black man seen on video gasping for breath as a white Minneapolis police officer knelt on his neck.
Protests also flared in Chicago, Seattle, Salt Lake City, and Cleveland.
Reuters contributed to this report.