The eruption of violence Monday in Baltimore, Maryland, was not condoned by the family of the young African American man at the center of the protests.
"I want you all to get justice for my son, but don't do it like this here," said Gloria Darden, the mother of 25-year-old Freddie Gray, who died while in police custody earlier this month.
"Don't tear up the whole city now, just for him," she added. "It's wrong."
Gray's twin sister, Fredericka, also spoke up at the New Shiloh Baptist Church Monday, saying she does not agree with the violence and accusing the rioters of acting not for her brother, but for a different reason.
"I think they're doing violence for something else," she said.
Earlier in the day, Baltimore Police reported on a "credible threat" that "members of various gangs" -- including the notorious Bloods and Crips -- had "entered into a partnership" to attack police.
"Law enforcement agencies should take appropriate precautions to ensure the safety of their officers," a police statement said.
The riots broke out after Gray's funeral Monday. Thousands of mourners had gathered to pay their respects to Gray, whose death has become the latest incident sparking outrage over interactions between police and minorities in the United States.
"We had a beautiful home-going service," said Gray's stepfather, Richard Shipley. "And to see that it turned into all this violence and destruction, I am really appalled."
Gray died of a severe spinal cord injury a week after his April 12 arrest. An attorney for his family said his spinal cord was 80 percent severed at his neck. It is unclear how Gray was injured, but officials said he was not wearing a seatbelt as he should have been while being transported in a police van.
Police Commissioner Anthony Betts said officers were slow to recognize that Gray, who apparently had asthma, needed medical attention.