NASCAR said in a statement that it was “made aware” of a noose that had been found in the garage stall of Bubba Wallace, the lone black driver in the organization’s Cup Series, during a race in Alabama on Sunday. An immediate investigation has been launched into the incident, NASCAR announced, stressing that there is “no place for racism” in the sport.

Wallace was equally outraged, writing on social media that he was “incredibly saddened” by the “despicable act of racism and hatred.” The 26-year-old lamented that the incident showed that the country was still struggling to overcome racism, but vowed that he would “never back down” and continue to stand against bigotry. Wallace had successfully campaigned to ban the Confederate flag from NASCAR events – leading some to speculate that the noose may be a retaliatory act aimed at intimidating the driver.

The race car driver was soon flooded with support from social media. Dave Zirin, sports editor for the Nation, praised Wallace for “standing up and speaking out in the violent, confederate confines of NASCAR.”

Basketball star LeBron James expressed solidarity with the driver, hailing him as an agent of change “in America and sports.”