Why did the riot happened? part 1

Why the riot started:
Hock Lee Amagamated Bus Company is made up of two Unions, The Hock Lee Employee's Union and The Singapore Bus Workers'' Union. Singapore Bus Workers' Union is actually founded by Fong Swee Suan and Lim Chin Siong, who both are communists. On April 23, 1955, workers from the Hock Lee Amalgamated Bus Company and some Chinese students began to go on strike. They were members of the Singapore Bus Workers' Union (SBWU) and were protesting against poor working conditions, long work hours and low pay. They also felt threatened by a rival union which was supported by the bus company to counter any labour action by SBWU. Futhermore, two-thirds of employees from the Hock Lee Employee's Union attempted to join the SBWU after the management of the Hock Lee Employee's Union did nothing to placate to their requests, through there were attempts from the Hock Lee Employee's Union to prevent them from joining the SBWU, some employees still joined the SBWU. Soon, they fired those workers who did it. Upon knowing that workers are dismissed, other workers were livid and soon all of them gathered at the company's depot in Alexandra and sat in front of the gates to prevent buses from leaving the garage. On 27 April 1955,the police were called in. The strikers blocked the gate and threw stones at the police.To dismiss the crowds, the police had to use batons to warn and clear them out of the garage. Due to this violence from both the police and the strikers, some 15 people were injured. Upon the news of strikers were injured, some 10,000 students from various Chinese school who sympathized with the workers came to their support arrived day after day in lorries.They showed their support by bringing food and entertaining the workers with songs and dance, thus more strikes in solidarity with the bus workers followed.