An illegal gambling den in Taichung, Taiwan, was raided during the early hours of Wednesday morning in an undercover police operation. As well as 23 Taiwanese suspected gamblers, four Vietnamese migrant workers were arrested.

After receiving tip-off reports, Wufeng Precinct of the Taichung City Government Police Bureau learned of a syndicate operating an illegal casino that frequently switched locations to keep ahead of the authorities, the United Daily News reported.

Two undercover officers pretending to be a couple were sent to collect intelligence and evidence.

After analyzing their officers’ intelligence reports, police raided an illegal gambling den in the early hours of January 10. There, a 51-year-old Taiwanese man surnamed Hsu who was identified as the syndicate leader and three alleged accomplices were arrested. Also seized as evidence were items used for gambling, security cameras and monitors and NT$514,200 (US$16,698) in cash.

Twenty-three Taiwanese men were arrested for participating in illicit gambling while four Vietnamese migrants who claimed only to be curious observers were also arrested, pending further investigations.