Hubli police on Wednesday arrested 4 persons on the charge of cheating foreign exchange agent in Hubli and seized Rs 6 lakh cash, eight cell phones and two two-wheelers. Hubli-Dharwad City Police Commissioner Narayan Nadmani told mediapersons that the accused had promised to sell gold at Rs 250 per gram to one Veerendra Kamat. When Kamat came with Rs 22.5 lakh cash to buy five kg gold, the accused tricked him and exchanged the bag with one containing paper, cut to currency note size.