Eight delegates arrived back in Regina on June 26. Attempts of the Trekkers to travel east by car or truck or train were thwarted by RCMP. A public meeting was called for July 1, 1935, 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 moving trucks were parked on three sides of the square concealing RCMP riot squads. Regina police were in the garage of the police station which was in Market Square. At 8:17 p.m. a whistle was blown, and the police charged the crowd with batons from all four sides. 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 started to use tear gas and fired guns. Driven from the Square, and with the RCMP blocking the roadway back to the Stadium grounds, the battle continued in the surrounding streets for six hours.

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, they were burned. 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, 140 Trekkers and citizens had been arrested. Charles Miller, a plainclothes policeman, died, and Nick Schaack, a Trekker, later died in the hospital from injuries sustained in the riot. There were hundreds of injured residents and Trekkers were taken to hospitals or private homes. Those taken to a hospital were also arrested. Property damage was considerable. The police claimed 39 injuries in addition to the dead police officer, but denied that any protesters had been killed in the melee; the hospital records were subsequently altered to conceal the actual cause of death.[citation needed]

Trekkers Arthur Evans and George Black who were on the speakers' platform were arrested by plainclothes police at the beginning of the melee.

The city's exhibition grounds were surrounded by constables armed with revolvers as well as automatic fire-arms.[citation needed] The next day a barbed wire stockade was erected around the area. News of the police-instigated riot was front-page news across Canada. About midnight one of the Trek leaders telephoned Saskatchewan 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 Hugh Guthrie made the false statement[citation needed][6] 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 lengthy 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."