On the night before 1 May 1921, the Jewish Communist Party (precursor of the Palestine Communist Party) distributed Arabic and Yiddish fliers calling for the toppling of British rule and the establishing a "Soviet Palestine". The party announced its intention to parade from Jaffa to neighbouring Tel Aviv to commemorate May Day. On the morning of the parade, despite a warning to the 60 members present from one of Jaffa's most senior police officers, Toufiq Bey al-Said, who visited the party's headquarters, the march headed from Jaffa to Tel Aviv through the mixed Jewish-Arab border neighbourhood of Menashia.
Another large May Day parade had also been organised for Tel Aviv by the rival socialist Ahdut HaAvoda group, with official authorisation. When the two processions met, a fistfight erupted, and the Palestine police chased the communists back to Jaffa.
Hearing of the fighting and believing that Arabs were being attacked, the Arabs of Jaffa went on the offensive. Dozens of British, Arab, and Jewish witnesses all reported that Arab men bearing clubs, knives, swords, and some pistols broke into Jewish buildings and murdered their inhabitants, while women followed to loot. They attacked Jewish pedestrians and destroyed Jewish homes and stores. They beat and killed Jews in their homes, including children, and in some cases split open the victims' skulls.
At 1:00 pm, an immigrant hostel run by the Zionist Commission and home to a hundred people who had arrived in recent weeks and days was attacked by the mob, and though the residents tried to barricade the gate, it was rammed open and Arabs attackers poured in. The stone-throwing was followed by bombs and gunfire, and the Jewish hostel residents hid in various rooms. When the police arrived, it was reported that they weren't shooting to disperse the crowd, but were actually aiming at the building. In the courtyard one immigrant was felled by a policeman's bullet at short-range, and others were stabbed and beaten with sticks. Five women fled a policemen firing his pistol; three escaped. A policemen cornered two women and tried to rape them, but they escaped. A fourteen-year old girl and some men managed to escape the building, but each was in turn chased down and beaten to death with iron rods or wooden boards.
As in the previous year's Nebi Musa riots, the mob tore open their victims' quilts and pillows, just like in the Russian pogroms, sending up clouds of feathers. Some Arabs defended Jews and offered them refuge in their homes; many witnesses identified their attackers and murderers as their neighbours. Several witnesses said that Arab policemen had participated.
High Commissioner Herbert Samuel declared a state of emergency, imposed press censorship, and called for reinforcements from Egypt. General Allenby sent two destroyers to Jaffa and one to Haifa. Samuel met with and tried to calm Arab representatives. Musa Kazim al-Husseini, who had been dismissed as Jerusalem's mayor on account of his involvement in the previous year's Nebi Musa riots, demanded a suspension of Jewish immigration. Samuel assented, and two or three small boats holding 300 Jews were refused permission to land, and were forced to return to Istanbul. At the same time, al-Husseini's nephew, Haj Amin al-Husseini, was appointed Grand Mufti of Jerusalem, a decision that later faced much criticism. Fighting went on for several days and spread to nearby Rehovot, Kfar Saba, Petah Tikva, and Hadera.
The riot resulted in the deaths of 47 Jews and 48 Arabs, with 146 Jews and 73 Arabs being wounded. Most Arab casualties resulted from clashes with British forces attempting to restore order.
Thousands of Jewish residents of Jaffa fled for Tel Aviv and were temporarily housed in tent camps on the beach. Tel Aviv had been previously lobbying for independent status became a separate city due in part to the riots. However Tel Aviv was still dependent on Jaffa, which supplied it with food, services, and was the place of employment for most residents of the new city.
The newspaper Kuntress, whose author and co-editor Yosef Haim Brenner was one of the victims of the riots, published an article entitles Entrenchment. The article expressed the view that the Jews' outstretched hand had been spurned but that they would only redouble their efforts to survive as a self-reliant community.
Some villages whose residents had participated in the violence were fined and a few rioters were brought to trial. When three Jews, including a policeman, were convicted of participating in the murder of Arabs, international outcry ensued. Although the Supreme Court ultimately acquitted them on grounds of self-defence, the incident served to continue the crisis of confidence between the Jewish community and the British administration. Three Arab men were tried for the murder of Brenner, but were acquitted due to reasonable doubt. Toufiq Bey al-Said, who resigned from the Jaffa police, was shot in the street; his assassin was dispatched by veterans of Hashomer in retribution for Brenner's murder, though another Jewish man was wrongly accused and acquitted.
Brenner was a critical and pessimistic figure, which perhaps made him all the more important and lent depth to the Zionist and Labor Zionist intellectual movement. His themes prefigure existentialist pessimism and nihilism. His first novel, Ba-Horef (in Winter) ends with the autobiographical hero, Feierman is forced to get off a train because he has no ticket. He is left stranded near a snow covered road in a forlorn place. The protagonists of his novels and stories all tend to share the same fate: aborted beginnings, unrealized hopes and goals, and bitterness and frustration. His first novel about Palestine, Mi-Kan Umi Kan (from Here and There) features Arieh Lapidot, a hero in the image of A.D. Gordon, who, together with his grandson, collect thorns for a fire to bake bread. "The old man and the youth were both crowned by thorns, as they stood the watch of life together. The Sun was shining, life was full of thorns. The account was still open." Thus wrote Brenner, epitomizing in many ways the nearly impossible life of the generation of the Second Aliya. [-]
Yosef Haim Brenner was murdered in a massacre by Arab rioters in Yaffo on May 2, 1921. Kibbutz Givat Brenner is named for him, as well as many streets.