The victim, now 21, "reluctantly" cooperated with police, DeMaio said. He has since moved out of the neighborhood where the beating took place out of fear of retaliation.
The victim's father apparently owed someone $20, prompting the beating, and the group took $10 from the young man, DeMaio said. He suffered welts and abrasions from the lashing but did not require hospitalization, DeMaio said.
The video incensed community members and law enforcement in the city, which has long grappled with violent crime and recorded 88 murders last year.
"It shows there is a brutal culture in this community," Booker said. "It's not the city's culture. But it is a subculture of violence and crime that we have to address. It's not just here in Newark."
Booker and DeMaio said they were disturbed that no one reported the beating, which took place on a warm August night and was witnessed by people who did not speak up until approached by police in February.
"When you witness something like this, stand up and speak up," Booker said. "That's what allows violence in the city to go on."
Holt was already in custody in Trenton on unrelated charges, DeMaio said. Clark was arrested, and Gray turned himself in with an attorney Tuesday night, DeMaio said.
The girlfriend of one of the suspects was arrested for heroin possession.