Reservist police officer Dennis Turner arrested the two children in separate incidents last Thursday, the Orlando police department told AFP in a statement.
Meralyn Kirkland, Kaia Rolle's grandmother, told local media her granddaughter suffered from sleep apnea and was acting up from a lack of sleep. She said a member of staff grabbed the girl by the wrists after she had acted up in class, and that the girl then kicked the person. Some media reports had suggested she kicked another student.
She said she was contacted by the school and that she tried in vain to dissuade the police officer from arresting the little African-American girl.
"I said, 'What do you mean, she was arrested?'" she told a local television news channel WKMG-TV. "They say there was an incident and she kicked somebody and she's being charged and she's on her way," When she told the police officer the girl suffered from sleep apnea, she said the policeman replied, "Well, I have sleep apnea, and I don't behave like that."
"No six-year-old child should be able to tell somebody that they had handcuffs on them and they were riding in the back of a police car and taken to a juvenile center to be fingerprinted, mug shot," the grandmother said.
Orlando police said the police van had turned back before reaching the juvenile center and the girl returned to school because Turner had not obtained the necessary permission from a supervisor to arrest a child aged less than 12 years.
The other six-year-old, however, was taken to a juvenile center before being released to the child's parents because the driver was not aware that he did not have the green light.
Turner was immediately suspended following the incident, the Orlando police department said. "As a grandparent of three children less than 11 years old, this is very concerning to me," police chief Orlando Rolon told the new channel.