Bernie Sanders was booed loudly during the Democratic presidential debate Thursday night when he refused to apologize to the victims of the Sandy Hook massacre for his stance on gun control.

In a tense moment, CNN moderator Wolf Blitzer challenged Sanders on his view that crime victims should not be able to sue gun makers for damages.

Blitzer said to Sanders, "The daughter of the Sandy Hook elementary school principal who was killed back in the 2012 mass shooting says you owe her and the other victims' families an apology. Do you?"

The Brooklyn debate audience booed Sanders as he initially avoided the question.

Pressed again by Blitzer, the Vermont senator said, "No, I don't think I owe them an apology. They are in court today, and actually they won a preliminary decision today. They have a right to sue, and I support them."

Sanders had said said that he voted against the gun liability law because he believed "that in rural areas all over this country, if a gun shop owner sells a weapon legally to somebody," the store owner should not be held responsible for what it later done with the gun.

"I don't believe it is appropriate that that gun shop owner ... be held accountable and sued," he said.

Rival Hillary Clinton has repeatedly attacked Sanders for his vote on the law, saying it shows he is in the pocket of the gun lobby.