One person was killed on Saturday, 25 July, and the suspect detained at a Black Lives Matter protest in Texas.
Footage posted during a Facebook Live showed the moment when several shots were fired in downtown Austin during a march by over 100 people, reported news agency Reuters.
Austin police and emergency medical services confirmed the news on Twitter. There were no other deaths reported.
Initial reports show the suspect was carrying a rifle and shot at the victim, who was in his car, police told in a briefing, reported Reuters. The suspect has been detained, they said.
Meanwhile, in Seattle, violence erupted between demonstrators and federal police agents during a march where thousands of protesters marched through the streets.
Officers resorted to using non-lethal weapons to disperse the crowds after a few protesters set fire to the construction site of a local juvenile detention centre and courthouse, DW reported.
Forty-five people have been arrested and 21 officers have sustained injuries, stated media reports.
Saturday saw a number of massive protests against racial injustice and police brutality, which have been triggered by the killing of the African-American George Floyd, who died in police custody in Minneapolis in May.
(With inputs from Reuters and DW)