New Jersey gambling regulators are looking into a sports betting tournament held over the weekend in which some competitors were unable to make bets on an NFL playoff game, costing them a shot at a $1 million top prize.

DraftKings apologized for the situation but said it had to follow its own rules.

“We recognize that in the rules the scheduled end of betting coincided very closely to the finish of the of Patriots-Chargers game,” said DraftKings spokesman James Chisholm. “While we must follow our contest rules, we sincerely apologize for the experience several customers had where their bets were not graded in time to allow wagering on the Saints-Eagles game. We will learn from this experience and improve upon the rules and experience for future events.”

DraftKings was not the only mobile sports book to experience problems on Sunday. FanDuel’s app and site went down for at least 45 minutes during the Saints-Eagles game, angering customers who were looking to make live in-game bets as it unfolded. FanDuel said Monday it is reviewing the cause of the incident.