One person was shot dead as President Donald Trump supporters and Black Lives Matter protesters clashed in the streets late on Saturday in the US city of Portland.

Police said the violence took place in Portland's downtown area and that they had made arrests.

"A political rally is caravanning throughout downtown Portland. There have been some instances of violence between demonstrators and counter-demonstrators," Portland police said on Twitter.

"Officers have intervened and in some cases made arrests."

"I can confirm a shooting, one person deceased, in the area of SW 3rd and Alder, and that we are in the early stages of a homicide investigation," a police representative was quoted as saying by KGW News.

It wasn't clear yet if the shooting was linked to fights that broke out as a caravan of about 600 vehicles was confronted by protesters in the area.

Demonstrations against racism and police brutality have swept the United States since the death in May of George Floyd, a 46-year-old Black man who died after a Minneapolis police officer knelt on his neck for nearly nine minutes.

Source: Agencies