One protester is in a critical condition after a "civilian on civilian" incident, the city said.
Riot police have lined the streets to face off against hundreds of protesters and tear gas has been fired.
Protesters are angry that a 43-year-old man, Keith Lamont Scott, was killed by police on Tuesday.
Police said Mr Scott had been repeatedly told to drop his handgun before he was shot.
But his family dispute that narrative and say he was reading a book.
His death sparked violent protests on Tuesday night, leaving 16 officers injured.