TAIPEI (Taiwan News) — The National Immigration Agency (NIA) detained 23 unaccounted-for Vietnamese workers living together in a building in Hsinchu County, reports said Friday (Aug. 19).

The sheet-metal building in the township of Xinpu was located behind a cemetery, farm land, and a pond, and was equipped with security cameras to monitor visitors, CNA reported. It had been divided into 10 rooms where the Vietnamese lived and worked, according to the report.

The NIA, the Coast Guard, and police formed a joint taskforce which raided the location early on Aug. 15. The residents were still sleeping when authorities arrived, though one worker jumped into a pond to escape arrest. An officer followed him into the water to apprehend him, the NIA said.

One of the detainees had illegally entered Taiwan, one was listed as wanted on drugs charges, but the other 21 were all unaccounted-for migrant workers. The NIA warned that anyone found guilty of harboring unaccounted-for foreigners could face fines ranging from NT$150,000 (US$4,990) to NT$750,000.