Mr. Farmer, who was taken to a hospital for treatment, did not have a previous history of seizures, Mr. Newhouse said, adding that he had been “seriously injured.”

“The WA police have one of the worst track records in this country for discrimination and prejudice against Aboriginal people,” he said. “The commissioner of police needs to come out with a very clear statement that violence against and harassment of Aboriginal people is not acceptable in his police force.”

West Australia’s police minister, Michelle Roberts, told reporters Tuesday that what happened was “very disturbing,” and pledged a thorough inquiry.

Others said the episode reflected a pattern of police mistreatment.

“This is not a singular incident. It has been going on for a very long time,” said Mr. Eades, chief executive of Ngalla Maya Aboriginal Corporation, adding that if it had not been caught on video, it would have never been made public.

He referred to other cases, like that of Ms Dhu, a young Indigenous woman whose family was awarded a 1.1 million Australian dollars (about $822,000) after she died in custody in 2014.

“This is systemic racism, and my people have been bearing the brunt of it, and we are sick of it,” he said.