Fifty kg of amphetamine, worth Rs. five crore, was seized by the directorate of revenue intelligence (DRI) in Padianallur. Four persons were arrested on Wednesday, in the connection with the incident, according to a press release. DRI officers, based on a tip-off, monitored trucks coming in to the city and found one truck from Punjab waiting at Padianallur. Subsequently, a sedan stopped near the truck and the contraband was exchanged. DRI officers caught the gang red-handed. Further investigation is on.