Malaysian police say they have rescued 21 Ugandan women who were lured to the country on false pretenses and forced into prostitution.

Investigators say the women, aged from 19 to 42, were freed last week from four apartment units on the outskirts of Kuala Lumpur. The women came to Malaysia via China, leaving their native country after being promised jobs as maids in hotels and homes.

Police say they were forced to become “sex slaves” in order to pay off $7,000 in travel fees. Officials said it was the first time they have uncovered a large-scale human trafficking ring involving Africans.

Police have arrested two Ugandan women on suspicion of running the prosititution ring, and a Ugandan man suspected of being a customer.

Human trafficking in Malaysia carries a prison sentence of up to 15 years.