Police got a foretaste of what the Occupy Central movement's planned civil disobedience campaign may look like when people who had joined yesterday's protest march stayed behind and practised their moves. They tried out body positions that would hinder police arresting them. And g roups of radicals disrupted traffic and impeded the flow on pedestrian walkways by walking up and down. Traffic on Pedder Street and Des Voeux Road nearly came to a standstill after the demonstrators began walking slowly back and forth on zebra crossings. League of Social Democrats lawmaker Leung Kwok-hung led one such group. Police repeatedly warned protesters against blocking traffic but they responded by walking even more slowly. Benny Tai Yiu-ting, an Occupy organiser, said he welcomed diverse ways of expression as long as they were non-violent. Earlier in the evening, people from a group calling itself the Hong Kongese Priority, some of whose members forced their way into the Central Barracks of the People's Liberation Army last Thursday, had planned to throw tomatoes on Pedder Street but were stopped by police. Four members were arrested. One of them, Tin Ki-yau, 17, was detained for disorderly behaviour, police said, after she ran onto the street draped in a colonial Hong Kong flag. The three others arrested, all male, were held for theft. Police said they had stolen Airport Express trolleys. While the call by marchers for a chief executive election without screening of candidates was loud and clear yesterday, protesters clashed among themselves over a number of issues, including whether newly arrived immigrants should be entitled to government benefits. "Implement universal suffrage for the chief executive as soon as possible. This is selfevident," chanted students from the Hong Kong Federation of Social Work Students, mocking Chief Secretary Carrie Lam Cheng Yuet-ngor's earlier remark that it was "self-evident" the chief executive must be a "patriot" - seen as hinting that screening is planned. A number of groups demonstrated in support of public nomination of chief executive candidates. The Democratic Party used the occasion to explain its "three-track proposal" under which nominations by the public, political parties and an election committee would all be considered acceptable. Some booed party leader Emily Lau Wai-hing when she said on stage that universal suffrage could still be achieved without public nomination. There was verbal abuse and scuffles between groups protesting for and against new immigrant rights. At Chater Garden in Central, anti-Beijing protesters surrounded Society for Community Organisation activist Richard Tsoi Yiu-cheong and criticised him for helping mainland migrant Kong Yunming apply for a judicial review of welfare rules. The legal action ended with the Court of Final Appeal ruling that new migrants are entitled to social security. One protester threw a placard at Tsoi. Police had to intervene to protect him. Activist priest Father Franco Mella, who has fought for years for right of abode for mainland-born children of Hong Kong residents, said: "They just don't understand what democracy is. I hope all Hong Kong citizens, including new immigrants, will enjoy equal rights when there is universal suffrage." About 20 people from the pro-establishment Defend Hong Kong Campaign set up a booth outside Southorn Playground in Wan Chai where they sang the national anthem and chanted slogans. When a protester waved a colonial flag, someone from Defend Hong Kong waved a large Chinese flag. Police stepped in.