Police staged an overnight clampdown on triad activities in Macau, questioning 1,300 people after a series of murders and attacks targeting casino customers and bosses over the past month. At least 150 people, including one suspect wanted in connection with a murder case in Hong Kong in 2009 were taken to police stations in the six-hour operation. Casinos and hotels were raided in the operation, which began late on Friday and ran into the early hours of yesterday. Almost 1,300 people were stopped for initial questioning by 210 officers, deployed in an operation codenamed Thunder 12, the Hong Kong China News Agency reported. While police have not given details of any specific crimes targeted in the operation, the Sunday Morning Post last week reported there had been three triad-style killings in a month and an attack inside a hotel that left a casino boss seriously injured. Cable Television reported that the suspect in the Hong Kong murder would be handed over to Hong Kong police for investigation. Hong Kong police had no comment on the suspect's arrest. One person detained was an illegal immigrant, while 18 others had exceeded their permitted stays in Macau, the news agency report said. The casino boss attacked was Ng Man-sun, the Mong Kok wet market trader turned casino boss who is known by the nickname 'Gai See Wai' or 'Street Market Wai'. He remains in stable condition in hospital under the protection of bodyguards after his brutal chopping in June by a gang of six men as he dined with a woman friend in a restaurant in Taipa. Ng is a major investor in the Greek Mythology Casino, which operates under Stanley Ho Hung-sun's SJM concession. The attack on him was followed by the killing of a mainland woman last month in a residential area minutes away from the Venetian Macao casino and came just days after two mainland men were murdered at the five-star Grand Lapa Hotel, formerly the Mandarin Oriental. The outbreak of violence has evoked memories of the late 1990s, when the then Portuguese-run enclave was rocked by assassinations, car bombings and gangland attacks as triads battled for control of lucrative VIP gambling rooms. Authorities in both Macau and the mainland are becoming increasingly jittery ahead of the release from prison later this year of the notorious 14K triad society boss 'Broken Tooth' Wan Kuok-koi, who wreaked havoc in the late 1990s.