A noose was found in Bubba Wallace's garage stall Sunday, according to a statement from NASCAR.
Wallace, who is the only Black driver in NASCAR's top circuit, has been very outspoken in the last few weeks about the Black Lives Matter movement and the corresponding protests. He even called on NASCAR to ban the Confederate flag, which they did on June 10.
"We are angry and outraged, and cannot state strongly enough how seriously we take this heinous act," NASCAR's statement read. "We have launched an immediate investigation, and will do everything we can to identify the person(s) responsible and eliminate them from the sport."
The racing organization also said the incident "only strengthens our resolve to make the sport open and welcoming to all."
Wallace took to Twitter Sunday, saying the "despicable act" left him "incredibly saddened and serves as a painful reminder of how much further we have to go as a society and how persistent we must be in the fight against racism."
"This will not break me, I will not give in nor will I back down. I will continue to proudly stand for what I believe in," Wallace said.
NASCAR told CNN the garage area where the noose was found is restricted to essential personnel, which includes race teams, NASCAR officials, security and health and safety personnel.
Sunday also saw the first time NASCAR fans returned to the track in Talladega, Alabama, where a Confederate flag with a "Defund NASCAR" banner was seen flying over the track. Confederate memorabilia was also being sold across the street.
The race was postponed to Monday due to weather, NASCAR announced.