A video showing an 8-year-old boy being shackled to a chair in school has ignited a firestorm over aggressive policing in public schools.

The video was entered as Exhibit A Tuesday in a lawsuit the ACLU filed against a Kentucky school, sheriff and officer. In the footage, you hear the sound of the young student whimpering and briefly hear the sound of metal handcuffs clanking as they close around the boy’s arms.

"You don't get to swing at me like that," a deputy says to the 8-year-old child, the interaction caught by a video camera. "You can do what we asked you to, or you can suffer the consequences."

The sheriff defended his deputy while experts believe that children shouldn’t be treated like adult criminals and bemoaned the lack of standardized regulations for restraining children.

"It was hard to breathe," David Shapiro, who leads the National Juvenile Defender Center's campaign against child shackling, said of his reaction when he first saw the video. "As someone who has acted out in class before, I really felt for that child. That's not the way to treat any child, in school, in court, or anywhere."

"Oh my goodness. Oh, no, this is not good," groaned Steven C. Teske, a Georgia juvenile court judge who has led the charge to reduce restraints in schools, as he watched the video for the first time while on the phone with The Associated Press.

Two mothers allege that school resource officer Kevin Sumner, a Kenton County deputy sheriff, handcuffed two children, the 8-year-old boy seen in the video and a 9-year-old girl in Covington Independent Public School district schools. Both children have been diagnosed with attention deficit hyperactivity disorder and are identified in court records by their initials. It’s unclear who took the video, which was filmed in August 2014.

The handcuffs were too big for the children’s wrist, so Sumner put the cuffs around their biceps, the lawsuit alleges.

In the video, the boy, who weighed 52 pounds, cried. "Ow, that hurts," he says.

The boy had been removed from class for failing to follow his teacher’s instructions, the lawsuit says. He tried to leave the principal’s office, so administrators stopped him until Sumner arrived. The officer took him to the bathroom and the boy tried to hit Sumner with his elbow.

Covington Independent Public Schools officials say that they were cooperating with investigators, but declined to discuss the incident out of privacy concerns.

School administrators' asked for his help after their "efforts to deescalate and defuse a threat to others had proven unsuccessful," Korzenborn said in a statement. "Deputy Sumner responded to the call and did what he is sworn to do and in conformity with all constitutional and law enforcement standards."

Kentucky state regulations ban school officials from restraining students in a public school unless the “students’ behavior poses an imminent danger of physical harm to self or others.” It also bans personnel from restraining students they know have disabilities that could cause trouble.

Officials in both schools were aware of the children’s disabilities, which include “impulsivity, and difficulty paying attention, complying with directives, controlling emotions and remaining seated,” the lawsuit says.

"An 8-year-old's job description is to be impulsive," said Julian Ford, a professor of psychiatry at the University of Connecticut.

Attention deficit hyperactivity disorder compounds that problem, he said, struggling to think of a scenario where handcuffing an 8-year-old might be necessary.

"It helps the adults a lot more than it helps the kid," he said.

In the video, the boy kicks his legs in the chair.

Sumner bends down and puts his hand on his shoulder.

"Look at me for a minute, look at me," he says. "If you want the handcuffs off, you've got to stop kicking. Do you want them off or not? It's up to you if you want them off."

"I'm devastated to see a child treated this way," said Lisa H. Thurau, founder Strategies for Youth, an organization meant to improve the relationship between children and police. "But this is not an isolated case. We've heard of these cases before."

Districts across the nation began placing officers in school in the early 1990s and the practice exploded after the Columbine High School massacre in 1999.

In the years since, the line between police officer and school administrator had been muddled, experts say. Schools now commonly call on their in-house officers to implement routine discipline.

At the same time, there has been no uniform method of training officers, no universal oversight or standardized guidelines, Thurau said.

Children with disabilities make up 12 percent of the public school population. But they make up 25 percent of all school arrests.

Thurau hopes that the video might spur the public to demand change.

"The video makes it very clear what's happening out there," she said. "And I think that there's an increasing awareness among folks that this has really, really got to stop."

The Associated Press contributed to this report.