WISCONSIN, United States - Two people have been killed and one injured during a third night of unrest in the US city of Kenosha, sparked by the police shooting of a black man.

Police said the three people were shot, but gave no details about who was involved.

Local media reports earlier said the violence was believed to have stemmed from a conflict between protesters and armed men guarding a gas station.

Unrest broke out in Kenosha after Jacob Blake was shot by police on Sunday.

People have since defied emergency curfews in the city to join protests, which at times have turned violent.

In their statement, Kenosha Police said officials responded to "reports of shots being fired and multiple gunshot victims" in the city at about 23:45 on Tuesday (04:45 Wednesday GMT).

"The shooting resulted in two fatalities and a third gunshot victim was transported to a hospital with serious, but non-life threatening injuries," the statement said.

It added that the identities of the victims were still being determined and that no further details would be given at this time. An investigation has been opened.

Footage shared online showed a man with a rifle being chased by a crowd before he fell to the ground and appeared to fire multiple rounds into the crowd. Other video shows armed civilians, many dressed in military fatigues, congregating outside businesses they said they were protecting.

Footage also shows people running through the streets as gunshots ring out, and wounded men on the ground.

The governor of Wisconsin said on Tuesday he was sending more National Guard troops to the city amid the unrest.(FA)