The rioting was sparked by rumors that a black Puerto Rican teenage shoplifter was beaten by employees at an S. H. Kress "five and dime" store.
The woman who had raised the alarm was arrested for disorderly conduct, the Kress Five and Ten store was closed early, and the crowd was dispersed by police.
After the rioting started, the police decided to get Rivera in order to show that he was unharmed but did not produce him until the next morning because the teen had given a fake address when first detained.
In the early evening, a group called the Young Liberators started a demonstration outside the store, quickly drawing thousands of people.
At some point, someone threw a rock, shattering the window of the Kress Five and Ten store, and the destruction and looting began to spread east and west on 125th Street, targeting white-owned businesses between Fifth and Eighth avenues.
The report identified "injustices of discrimination in employment, the aggressions of the police, and the racial segregation" as conditions which led to the outbreak of rioting.
The report congratulated the Communist organizations as deserving "more credit than any other element in Harlem for preventing a physical conflict between whites and blacks".