They reportedly extended 20 million baht in loans to 1,246 people over the past couple of months in nine areas in Bangkok and its vicinities.
They are Bang Bon, Lat Phrao, Don Muang, Nakhon Pathom, Bang Bua Thong, Lam Luk Ka, Ram Intra, Klong Toey and Nimat Mai.
The suspects allegedly extended 5,000 to 10,000 baht to each borrower and collected repayments of 200-400 baht a day.
Some of the 10 suspects also reportedly extorted protection money from motorcycle taxi riders.
The police seized 12 motorcycles, three cars, four pickup trucks, 20 ledgers, guns and bullets and 95 krathom (Mitragyna speciosa) leaves from their house.
They were charged with charging illegal interest rates, operating an illegitimate personal loan business and having arms in possession without licences.