Four Chicago Blackhawks fans were ejected from United Center on Saturday for heckling Washington Capitals forward Devante Smith-Pelly.
Off-ice officials heard spectators taunting Smith-Pelly, who is black, while he was in the penalty box by repeatedly yelling the word "basketball".
Smith-Pelly heard the taunt and got up to confront one fan through the glass but was quickly turned around by the penalty box attendant.
A statement from the Blackhawks read: "We were made aware of an incident at tonight's game involving a small group of attendees who made harmful comments directed at Washington Capitals player Devante Smith-Pelly.
"The fans were immediately removed and we apologise to Smith-Pelly and the Washington Capitals organisation. We are committed to providing an inclusive environment for everyone who attends our games and these actions will never be tolerated."
"There's absolutely no place in the game of hockey or in our country for racism," Capitals coach Barry Trotz said following Washington's 7-1 loss to the Blackhawks. "I think it's disgusting.
"Athletes in our country don't deserve that. It just shows ignorance."