CHICAGO, Sept. 5 (Xinhua) -- Hundreds of protesters gathered Saturday evening outside the racecourse where the 146th Kentucky Derby was held in Louisville in the U.S. state of Kentucky to demand justice for Breonna Taylor, an African-American woman killed by police.

Protesters stood outside the racetrack fences, calling for justice for the shooting death of Taylor during a police raid and for the Derby to be canceled. A plane dragging a banner saying "arrest the cops who killed Breonna Taylor" flew overhead just a few minutes before the Derby race was set to begin, local media reported.

Protesters left the racecourse and continued their march shortly after the Derby ended.

Earlier Saturday, armed counter-protesters confronted a group of demonstrators downtown. Then the group engaged another one coming from Jefferson Square. Louisville Metro Police Department (LMPD) officers worked to separate the two groups of protesters and ease the tensions, police official account tweeted.

Louisville Mayor Greg Fischer warned on twitter Saturday that the Louisville police department "has a plan and is ready for Kentucky Derby day."

Kentucky Attorney General Daniel Cameron tweeted Saturday: "Today, while we honor a KY tradition with the running of the Derby, we remain cognizant of the community's desire for answers in the investigation into the death of Ms. Breonna Taylor," adding that "we continue to move forward with our investigation, reviewing each fact to reach the truth."

Taylor, 26, was fatally shot by several LMPD officers on March 13 when they were executing a "no-knock" search warrant at her apartment, and gunfire broke out after her boyfriend fired a warning shot because he thought the plainclothes officers were intruders.

Kentucky Derby is one of the three legs of the American Triple Crown, open to three-year-old Thoroughbreds. The race is traditionally held on the first Saturday in May, but the 2020 running was rescheduled to Saturday, due to the COVID-19 pandemic, and ran without spectators.