Chandigarh: The Border Security Force troopers on Wednesday seized several packets of heroin after exchanging fire with smugglers from the Pakistani side of Punjab's Gurdaspur, an official said. The BSF official said that alert troopers near the Chautra border out post (BoP) noticed activity across the barbed wire fence early on Wednesday through night vision devices. The suspected smugglers were challenged, who opened fire at the BSF. The security forces returned the fire, following which the smugglers fled towards Pakistan. A search operation in the area lead to the recovery of five packets of heroin weighing five kg, the official said.