North Carolina authorities investigating the use of child labor by what they're calling an "alternative religious group" have arrested four more people.

Cumberland County Sheriff Ennis Wright announced Friday that the four suspects had turned themselves in. Two were charged with involuntary servitude of a minor, among other charges. Another was charged with child abuse and a fourth faces charges including conspiracy.

The sheriff's office said Wednesday that a religious leader was operating several fish markets in the Fayetteville area, using the labor of children as young as 9 who received little or no pay. The children had to lift heavy boxes and clean and cut fish, according to a news release. Four suspects were arrested earlier this week.