Until 10 PM, the riot centered on 125th Street, and on police efforts to disperse crowds. Rather than ending the public disorder, police activity only escalated the violence, leading to attacks on Kress’ spreading to the other large stores that had been the targets of the boycott movement. After police cleared the street around 7pm, they set up in front of Kress to protect the store, and tried to keep crowds from gathering by firing shots in the air and riding horses on the sidewalks to keep people moving. However, large crowds remained on 7th and 8th Avenues, where police had pushed them in clearing 125th Street, while others reassembled on 124th Street, at the rear of Kress’ store. When violence broke out there after the appearance of a hearse added credence to calls that Rivera was dead, police who came to clear the street were met with a barrage of missiles (including, according to some reports, from above, from roofs, as well as hallways). At least 4 officers were injured.
With more officers arriving, police tried to extend cordon protecting Kress’ to the blocks of 124th and 125th Streets between 7th and 8th avenues. However, the crowd had also grown. Rumors spreading through Harlem, and the gun shots and outcry generated by clashes with police, drew an audience from the large population of unemployed on Harlem’s streets – adults who in the 1920s would have been out of the neighborhood at work rather than on home relief within its boundaries. Flyers distributed by the Communist Party attracted others. The few hundred police could not control the thousands who milled along 125th Street. Windows were smashed in stores surrounding Kress on 125th St; by 10pm, all the store windows the length of 125th Street from 7th to 8th Avenue had been broken. At 9 PM, with additional reinforcements, police tried to further extend their cordon and disperse crowds on 7th Avenue and 8th Avenue. They concentrated men and riot control trucks (Emergency Service Units) at 125th St and 7th Avenue where the crowd was largest, stationed additional trucks at key intersections north of 125th street on the Lenox, 7th and 8th avenues, and sent patrol cars, undercover officers, and mounted police through this area.
While the police occupied the attention of most of those gathered on the streets, groups in the crowds began to target whites they encountered. Around this time occurred the only reported instance of police firing at individuals before midnight, when officer George Conn shot at a group of black men attacking a white man, Timothy Murphy. Conn had been brought in from a precinct outside Harlem; such officers had a reputation for particular brutality in their dealings with blacks. His shots hit Paul Boytt, a 28 year old who lived a few buildings down the street from the site of the attack. According to Murphy, he was on his way home when a group of twelve black men attacked him, announcing that “they were beating me because I was a white man.” The New York Times reported that police also broke up additional attacks on whites These attacks are a reminder that if black residents saw police as representatives of white authority, as accounts of commodity riots emphasize, their antagonism towards them was not somehow demarcated from a broader racial antagonism. Anger at white police flowed into anger at whites.