Macau authorities have broken up a group of loan sharks that preyed on casino dealers.

On Monday, Macau Business Daily reported that local police had arrested 10 individuals suspected of targeting casino staff, particularly dealers, with high-interest loans. The group has reportedly been operating in Macau for around five years and police aren’t ruling out further arrests.

Acting on a tip-off received this February, police mounted raids on multiple locations last week. The raids turned up evidence that the group had about 120 debtors currently owing around MOP 4m (US $500k). In addition to computers and other records, police also seized a cache of debtors’ bankcards and employee ID cards.

Police said the sharks required debtors to surrender their employee ID cards until their debt was repaid. If the debtor was having difficulty repaying the debt, the sharks would send four or five people to the individual’s station at the casino to demand repayment and cause a disturbance as an extra incentive to make with the money.