Trump threatens to deploy troops as police tear gas protesters

US President Donald Trump said he is mobilising "all available federal resources" to end nationwide riots triggered by the death of George Floyd.

Trump said he urged governors to "deploy the National Guard in sufficient numbers so that we dominate the streets." The president said he would "deploy the United States military" if they do not take action.

He described attacks on law enforcement agents as "domestic terror." However, he did not acknowledge that the initial protests were triggered by Floyd's death in police custody.

"These are not acts of peaceful protest," Trump said. "These are acts of domestic terror. The destruction of innocent life and the spilling of innocent blood is an offense to humanity and a crime against God."

"What happened in the city last night was a total disgrace," he said as tear gas went off and crowds protested in the streets nearby.

"I am dispatching thousands and thousands of heavily armed soldiers, military personnel and law enforcement officers to stop the rioting, looting, vandalism, assaults and the wanton destruction of property."

He also named Antifa, an anti-fascist movement, as a chief "instigator" of the protests.

George Floyd death was homicide: Official autopsy

The Hennepin County medical examiner on Monday declared the manner of George Floyd's death to be a "homicide."

"Decedent experienced a cardiopulmonary arrest while being restrained by law enforcement officer(s)," the examiner said.

Cause of death was listed as "cardiopulmonary arrest complicating law enforcement subdual, restraint and neck compression.''

The statement added that "manner of death is not a legal determination of culpability or intent."

Under "other significant conditions'' it said Floyd suffered from heart disease and hypertension, and listed fentanyl intoxication and recent drug use.

The declaration comes after the family of George Floyd received an autopsy report showing that he died of suffocation. The finding contrasts an official ruling that he had died from pre-existing heart problems.

"Independent medical examiners who conducted an autopsy of Floyd on Sunday determined that asphyxiation from sustained pressure was the cause of death," said Ben Crump, a lawyer for the family.

The death of Floyd, an unarmed African American, during his arrest by a white police officer has triggered a wave of protests and riots across US cities.