A CNN news crew covering protests in the US city of Minneapolis, Minnesota, has been arrested on air in a shocking escalation of tensions in the troubled city. 

Reporter Omar Jimenez and two colleagues were handcuffed while doing a live broadcast at the site of violent protests in the city. The protests were triggered by the death of George Floyd who died after a fatal encounter with Minneapolis police.

The incident was captured on video by an onlooker. In the shocking video, a handcuffed Floyd can be heard groaning for help and repeatedly saying “please, I can't breathe" while a police officer kneels on his neck.

The 46-year-old, who was unarmed and allegedly suspected of trying to pass counterfeit bills at a corner eatery, was taken by ambulance from the scene of his arrest and pronounced dead on the same night in a hospital.

The officers implicated in his death have since been fired. 

It remains unclear why the CNN trio were arrested, but the broadcaster has since demanded their immediate release while labelling the arrests "a clear violation of their First Amendment rights".

- Additional reporting by Reuters