Troubled flared in Baltimore hours after the funeral of Freddie Gray, who died after he was arrested by police on April 12th.
It is alleged he was held down, handcuffed and loaded into a van without a seat belt.
Almost 3,000 people packed New Shiloh Baptist church for his funeral before spilling out onto the streets to protest.
Peaceful demonstration soon turned to chaos with police cars set ablaze, windows smashed and buildings looted.
Revd Jamal Bryant said it was "disappointing" and that he was hoping to bring some "calm" but added he "doesn't know what to say".
"This is not what the family asked for, today of all days," he said.
"To walk into this is absolutely inexcusable, I'm asking every young person to go home.
"Tomorrow night we'll have a community meeting for us to recalibrate because peace is the call and the order of the day."
He added that the riots followed rising "frustration and anger".
"What has happened today is not peaceful and it does not reflect the spirit and the heart of this movement."
The mayor of Baltimore has declared a state of emergency and imposed a daily curfew from 10pm to 5am.