Police arrested a CNN crew broadcasting live from the US city of Minneapolis early on Friday while covering unrest sparked by the death of a black man at the hands of law enforcement.

The crew was later released.

The network posted footage of correspondent Omar Jimenez speaking calmly to police with batons and riot helmets, then being handcuffed and taken away.

"Do you mind telling me why I am under arrest, sir," Jimenez is heard saying. "Why am I under arrest, sir?"

No answer was audible.

CNN said a producer and a camera operator working with Jimenez were also arrested.

Earlier, as Minnesota state police surrounded Jimenez while he reported, the correspondent spoke to the officers and said he wanted to cooperate.

"Wherever you want us, we would go," said Jimenez, who is black. CNN said in a tweet that a white reporter who was also on the ground covering the unrest was not arrested.

Jimenez was back on the air later Friday after police released him. CNN said Minnesota Governor Tim Walz apologized to the network.

Earlier, CNN put out a statement condemning the police behavior.

"A CNN reporter & his production team were arrested this morning in Minneapolis for doing their jobs, despite identifying themselves - a clear violation of their First Amendment rights," the network said.

Jimenez was in the city covering the third straight night of unrest triggered by the death of George Floyd after he was arrested on suspicion of using a counterfeit banknote.

A video taken by a bystander shows an officer kneeling on his neck as he is pinned to the ground. At one point Floyd is heard saying he cannot breathe, and eventually his body goes limp.