Chicago police urged the public on Wednesday to come forward with any information about a burning cross — a historic symbol of hate and intimidation against Black Americans — discovered at a popular downtown park.

A community alert issued by police included an image of a person walking away from the area, where on Tuesday afternoon bystanders were shocked to see the cross on fire.

Police said the person was seen “fleeing from the scene” where an object was constructed and burned in Grant Park. The alert provided no update on the arson investigation, but police advised community members to pay attention to and report suspicious activity.

The Chicago Fire Department confirmed the flaming object was a cross, and said officials put out the fire.

A video taken by a motorist circulated widely online Tuesday showing the wooden cross engulfed in bright orange flames as it leans against a tree.

Keinika Carlton, 43, was driving home from running errands with her daughter and mother-in-law when they saw the cross on fire. She said she felt a combination of shock, sadness, disgust, as well as curiosity.

“Is this a racial thing? Is this a religious thing?” she said. “As Black women, of course, our first thought is racial, because burning crosses are known to be used as a tactic, an act of violence toward Black Americans in the South.”

Carlton estimated the cross was at least 6 feet (1.8 meters) tall. As they slowed down to shoot a video of the flames, she saw other cars also slowing down and people walking nearby, staring at the cross burning.

While the motive behind the burning cross was not immediately clear, cross burnings in the U.S. have historically been seen as “symbols of hate” that are “inextricably intertwined with the history of the Ku Klux Klan,” according to a 2003 U.S. Supreme Court decision written by the late Justice Sandra Day O’Connor. The justices ruled that the First Amendment allows bans on cross burnings only when they are intended to intimidate because the action “is a particularly virulent form of intimidation.”

Alyna Carlton, 22, said she never thought she would see something like that in her lifetime.

“It kind of really opened my eyes, had me realize that I’m not that far removed from the past.”