A two-day undercover operation by police investigating social media and online dating services led to the arrest of 19 people who were charged with soliciting and prostitution on Saturday.

The 19 people arrested, aged between 16 and 40, included a 30-year-old Indonesian domestic worker and a 40-year-old Indonesian woman whose employment contract had just finished and whose visa had expired.

The investigation started when police were alerted to the terms “compensated dating” and “part time boyfriends or girlfriends,” which appeared on social media, mobile phone applications and online datings services but turned out to be fronts for people offering sexual services, the Apple Daily reported.

After a month-long investigation, officers then went undercover posing as customers and arrested the 19. Six “part time boyfriends” and six “part time girlfriends,” including a 16-year-old girl who dropped out of school as well as three male students from a secondary school, a vocational training council institute and a tertiary institute and a man who claimed to be an engineer, were arrested for allegedly soliciting for an immoral purpose, the Apple Daily reported.

A 29-year-old local man was also arrested on suspicion of being a middleman and controlling two men aged 22 and 23 who worked as “part time boyfriends,” the Oriental Daily reported. Those arrested were accused of charging between HK$1,000 and HK$4,000 (US$127 and US$509) for servicing customers.

Six men were also arrested and accused of being customers. Officers also confiscated several mobile phones, backpacks, condoms, lubricants and uniforms during the operation.

Read: Police nab 10 ‘part-time girlfriends’ in online sex sting