Last updated at 6.59pm: Police on Friday afternoon confirmed five people had been arrested for involvement in a vicious attack on pro-democracy legislator Albert Ho Chun-yan in a crowded fast-food restaurant in August. Three men and one woman were arrested in Sham Shui Po and Kowloon Bay on Wednesday, head of the Hong Kong Island regional crime unit Senior Superintendent Ma Wang-chow said. A fifth man was arrested in the mainland. 'Simultaneously, we requested our counterparts in the mainland to arrest a man in Zhongshan,' Mr Ma said. The suspects, all Hong Kong residents, are aged 27 to 57. They were still being detained on Friday afternoon, Mr Ma said. He said police believed the four men actually carried out the attack. Mr Ma declined to comment whether there was still any suspect at large but said police were investigating the motive for the attack. Mr Ho, a vice-chairman of the Democratic Party, was beaten by baton-wielding thugs in a McDonald's outlet in Central on August 20. The attack occurred in the afternoon, after he had participated in a street protest. The assailants, wearing caps to hide their faces, fled after the minute-long attack. On Friday afternoon, detectives brought one of the suspects to the waterfront at the Sai Kung Pier - where they allegedly disposed of their weapons - to reconstruct the details of the case. Mr Ho welcomed the arrest of the suspects but said it was too early to say whether the investigation would end successfully. 'The next step is to see whether police have enough evidence to proceed to arrest the person who masterminded the attack,' he said. Local newspaper reports said the suspects had returned from Shenzhen, where they fled following the brutal attack. Apple Daily, citing unnamed police sources, said detectives tracked down the suspects based on fingerprints from a police baton allegedly left behind by assailants. Four days after Mr Ho was attacked, a note with a death threat and a knife blade was sent to his law firm. The note warned him to 'watch his step', saying he would 'not be as lucky next time'. One of Mr Ho's legal cases police were looking into was Winnie Ho Yuen-ki's ongoing legal battle with her estranged brother, Macau casino mogul Stanley Ho Hung-sun. A lawyer working on the case was previously attacked and suffered head injuries.