Two policemen were shot amid protests in the US over a decision not to charge any officers over the killing of Breonna Taylor.
Officers shot do not have life-threatening injuries and a suspect has been arrested.
A state of emergency has been declared and the National Guard has been deployed. A three-day curfew from 21:00 to 06:30 has been introduced, though crowds were still gathered after it came into effect.
Police say at least 127 arrests were made in Louisville overnight. Most arrests were for breaking the curfew.
According to the Associated Press, the attack happened as protesters were moving through an alleyway to avoid a police roadblock as officers threw pepper balls at them. As shots rang out, the crowd scattered to take cover as officers in riot gear and rifles swarmed the area.
Protests over the grand jury’s decision also took place in New York, Washington, Atlanta, and Chicago.
Breonna Taylor’s Killing:
Ms Taylor, 26, a black hospital worker, was shot six times as three officers raided her home on 13 March.
A grand jury in the city of Louisville returned only one minor charge against one of the officers, for shots which hit a neighbouring apartment.
The attorney general said the two other officers’ actions had been justified.
One had been hit by a shot fired by Ms Taylor’s boyfriend, who later told police he thought it was an ex-boyfriend of Ms Taylor who had broken into the apartment.
A judge had granted a warrant to search Ms Taylor’s home because investigators suspected her ex-boyfriend, a convicted drug dealer, was using the address to receive packages. Ms Taylor had no criminal record.
Cases of killings of unarmed black people by police have fuelled anger across the US and beyond, spurred especially by the death of George Floyd in police custody in Minneapolis in May.