(Reuters) - Bill Clinton faced down protesters for 10 minutes at a presidential campaign rally in Philadelphia for his wife, Hillary Clinton, over their criticisms that a 1994 crime bill he approved while president led to a surge in black people being imprisoned.

Several protesters heckled him and held signs, including one that read “CLINTON Crime Bill Destroyed Our Communities.”

Video footage of Hillary Clinton defending the bill in 1994 by calling young people in gangs “super predators” who need to “be brought to heel” have been widely circulated during the campaign by activists in the Black Lives Matter protest movement.

Bill Clinton defended her 1994 remarks, which protesters say were racially insensitive.

“I don’t know how you would characterize the gang leaders who got 13-year-old kids hopped on crack and sent them out on the street to murder other African-American children,” he said, shaking his finger at a heckler as Clinton supporters cheered, according to video of the event. “Maybe you thought they were good citizens. She didn’t.”

Hillary Clinton, who also has faced protesters upset by her remarks, has said she regrets using the term.

Bill Clinton said last year that he regrets signing the Violent Crime Control and Law Enforcement Act into law because it contributed to the country’s high incarceration rate of black people for nonviolent crimes.