Upon returning to Regina to unite with the rest of the protesters on July 1, 1935, a public meeting was called in Market Square in Germantown (now the site of the Regina City Police station) to update the public on the progress of the movement. It was attended by 1,500 to 2,000 people, of whom only 300 were Trekkers. Most Trekkers decided to stay at the exhibition grounds.
Three large vans were parked on the sides of the square concealing RCMP riot squads. Regina police were standing by in a nearby garage. At 8 p.m. a whistle was blown and the police charged the crowd, setting off hours of hand-to-hand fighting throughout the city's centre. The attack caught the people off guard before their anger took over. They fought back with sticks, stones, and anything at hand. Mounted RCMP officers then charged into the crowd and attacked with clubs. Driven from the Square, the battle continued in the surrounding streets for four hours. Trekkers on the speakers' platform were arrested by plainclothes police.
Police fired revolvers above and into groups of people. Tear gas bombs were thrown at any groups that gathered together. Plate glass windows in stores and offices were smashed, but with one exception, these stores were not looted. People covered their faces with wet handkerchiefs to counter the effects of the tear gas and barricaded streets with cars. Finally the Trekkers who had attended the meeting made their way individually or in small groups back to the exhibition stadium where the main body of Trekkers were quartered.
When it was over, 120 Trekkers and citizens had been arrested. One plainclothes policeman had been killed, and one protestor would later die in the hospital from injuries sustained in the riot. Hundreds of injured local residents and Trekkers were taken to hospitals or private homes. Those taken to hospital were also arrested. Property damage was considerable. The police claimed 39 injuries in addition to the dead police officer, but denied that any protestors had been killed in the melee; the hospital records were subsequently altered to conceal the actual cause of death.
The city's exhibition grounds were surrounded by constables armed with revolvers and machine guns. The next day a barbed wire stockade was erected around the area. The Trekkers in the stadium were denied any food or water. News of the police-instigated riot was front page news across Canada. About midnight one of the Trek leaders telephoned Premier Gardiner, who agreed to meet their delegation the next morning. The RCMP were livid when they heard of this and apprehended the delegates for interrogation but eventually released them in time to see the premier.
Premier Gardiner sent a wire to the Prime Minister, accusing the police of "precipitating a riot" while he had been negotiating a settlement with the Trekkers. He also told the prime minister the "men should be fed where they are and sent back to camp and homes as they request" and stated his government was prepared to "undertake this work of disbanding the men." An agreement to this effect was subsequently negotiated. Bennett was satisfied that he had smashed what he believed was a communist revolt and Gardiner was glad to rid his province of the strikers.
The federal Minister of Justice made the false statement in the House of Commons on July 2 that "shots were fired by the strikers and the fire was replied to with shots from the city police." During the long trials that followed, no evidence was ever produced to show that strikers fired shots during the riot. For his part, Bennett characterized the On-to-Ottawa Trek as "not a mere uprising against law and order but a definite revolutionary effort on the part of a group of men to usurp authority and destroy government."