TULSA, Oklahoma (CNN) -- Hundreds of people, both black and white, attended an emotional "assembly of repentance" Monday, in a bare lot where Tulsa's thriving black business district once proudly stood.

The event was to mark the 77th anniversary of one of the nation's worst race riots, which occurred on June 1, 1921. The riot broke out when mobs called for the lynching of a black man accused of attacking a white elevator operator. When the smoke lifted the next day, the Greenwood district lay in ruins and dozens lay dead. The death toll was put as high as 300.

During Monday's ceremonies, white ministers led whites in seeking forgiveness for the actions of their forefathers, and black ministers led a smaller crowd of blacks in pardoning them.

For Mabel Little, a 101-year-old survivor of the riots, seeing the races shoulder to shoulder was a blessing. "I'm the happiest person in the world, today," she said.