George Floyd: Police officer shot during Las Vegas protests

Protests have erupted across the US following the killing of unarmed African American man George Floyd

An officer has been shot in Las Vegas and police are responding to another shooting as people protest the killing of George Floyd in Minneapolis, authorities said.

One officer was shot on the Las Vegas Strip and a second officer was involved in a shooting in the downtown area, according to the Las Vegas Metropolitan Police Department.

Police in Las Vegas said Monday that 338 people were arrested during three nights of protests. Officers used tear gas and pepper balls to disperse crowds late Saturday downtown and Sunday on the Las Vegas Strip.

Police said suspects were jailed despite a local court policy calling for most people accused of misdemeanour crimes to receive court summonses instead of time behind bars to help prevent the spread of the new coronavirus.

Protesters have been rallying for days across the country over the death of Floyd, who was seen on video pleading that he couldn't breathe with a white police officer pressing his knee into his neck for several minutes before Floyd stopped moving.

Tuesday marks the sixth straight day of unrest following Floyd's death, with curfews now imposed in New York City and Los Angeles.

Despite the rising tensions, president Donald Trump has threatened to deploy the military after accusing state governors of failing to bring the protests under control.

In an audio recording leaked on Monday, Mr Trump can be heard calling the governors "weak" as he urged them to act more aggressively.

He said the protests are ruining the nation's standing on the world stage. And he called on governors to pass new bans on flag burning, a constitutionally protected expression of free speech.

A protester prays in front of George Floyd's memorial in Minneapolis (AFP via Getty Images)

"Washington was under very good control, but we're going to have it under much more control," Trump said, according to audio of the meeting obtained by CBS News.

"We're going to pull in thousands of people." He added later: "We're going to clamp down very, very strong."

On Monday, a lawyer for the Floyd family said that an independent autopsy showed that Mr Floyd died from asphyxiation caused by neck and back compression when he was arrested on Memorial Day.

Medical examiners found that pressure to Floyd’s carotid artery (blood vessels that carry oxygen-rich blood to the head) had been impeded, affecting his ability to breathe.

Taking account of all the evidence, doctors Michael Baden and Allecia Wilson concluded that Floyd had died at the scene.

"What we found is consistent with what people saw. There is no health issue that could cause or contribute to the death," Dr Baden said.

"Police have this false impression that if you can talk, you can breathe. That's not true."

Attorney Ben Crump has called for sacked officer Derek Chauvin to be charged with first rather than third degree murder.

Protestors are also calling for charges to be brought against the three other officers accompanying Mr Chauvin when he made the arrest.