The FBI and the US Justice Department say they have opened a civil rights investigation into the violent arrest of a black female high school student by a white police officer, footage of which has gone viral and sparked outrage.
The incident in South Carolina comes amid a heightened focus on police brutality in the United States after a string of incidents - some deadly - involving police and African Americans.
Politicians, school officials and rights groups expressed outrage on Tuesday (local time), saying such violence has no place in schools.
In two mobile phone videos of Monday's confrontation in the state capital Columbia, an officer has a short conversation with a girl, sitting at her desk, before grabbing her by the neck, flipping her and her desk over, and dragging her along the floor.
She does not appear to put up any resistance, though Richland County Sheriff Leon Lott said Tuesday he had learned of a third video of the incident, from a different angle, that shows the student hitting the officer.
School officials called the incident shocking.
"It was outrageous and unforgivable, and it does not represent who this district is," Debbie Hamm, superintendent of Richland School District Two, told reporters Tuesday.
She said there is strict protocol to ensure that the police officers assigned to the school only intervene in criminal behaviour and not disciplinary incidents.
"Regardless of the reason for the officer's actions, such egregious use of force - against young people who are sitting in their classrooms - is outrageous," Victoria Middleton, executive director of the rights group American Civil Liberties Union, said in a statement.
The civil rights investigation is being conducted by the Columbia field office of the Federal Bureau of Investigation, the bureau's Civil Rights Division and the US Attorney's Office for the District of South Carolina, the FBI and DOJ confirmed Tuesday to AFP.
Lott said the officer has been suspended without pay and that an internal investigation to determine whether there were any violations of use-of-force policy would be wrapped up within the next 24 hours.
The sheriff also said the student was not injured as far he knew, though "she may have had a rug burn or something like that," and that whether or not she hit the officer was not relevant to his investigation into whether the officer should keep his job.
Hillary Clinton, the frontrunner for the Democratic presidential nomination, also tweeted her outrage on Tuesday.