Two young men were arrested yesterday in connection with the Causeway Bay acid attack last month - the first arrests following a spate of such attacks across Hong Kong since December 2008. It was not immediately known if they are connected to any of the other attacks, several of which, like the one in Causeway Bay, targeted pedestrianised urban streets. The attacks have injured more than 100 people. The men, aged 23 and 18, were arrested in Yuen Long, and police said they were friends. Senior Superintendent Yu Tat-chung of the Hong Kong Island crime unit said it was unclear whether the two men were linked to the other 10 incidents. 'We are still investigating whether they had anything to do with the other cases,' he said. Officers took the 23-year-old to his home in Yiu Fu House on the Yiu Tung Estate in Shau Kei Wan for further investigation last night. Officers removed items from the flat including clothing. The younger man was freed on police bail. Eight of the acid attacks were carried out in popular shopping districts including Mong Kok and Sham Shui Po, and three on housing estates in Tuen Mun and Tin Shui Wai. The acid attack in Causeway Bay on December 12 was the first on Hong Kong Island. Six people were hurt in the incident, two of them seriously, when acid was thrown from an old building and showered a pedestrianised section of Lockhart Road near the Sogo department store just after 10pm. Causeway Bay was particularly busy that night with people celebrating the Hong Kong soccer team's victory over Japan in the East Asian Games final at the Hong Kong Stadium in So Kon Po, and with visitors to the annual Hong Kong Brands and Products Expo in Victoria Park, which opened its doors to the public. The first attack occurred in Mong Kok on December 13, 2008, followed by another two in the same area in May and June last year. No one was hurt in three attacks in Sham Shui Po in June and October. The latest attack occurred on Saturday at the Temple Street night market in Yau Ma Tei, in which 30 people were injured, including nine tourists. The area is a popular tourist spot. Police suspect the same perpetrator was involved in the five attacks in Mong Kok, Causeway Bay and Yau Ma Tei. The attacks were on busy pedestrian areas, were carried out from old buildings with lax security and involved the same kind of acid. In each case, two bottles were thrown. Acid drills suggested C2