Armed robbers, clad in police uniforms, forcibly stopped the cash van of a private bank near Punjab's Ludhiana city on Monday, and escaped with cash amounting to Rs.1.68 crore, police said.The incident took place on the Ludhiana-Ferozepur highway near Nanaksar village, 150 km from here.The staff of the cash van told police that the robbers came in another vehicle and stopped them."They were wearing police uniforms. They forced our vehicle to stop, locked us inside it and took away the cash," one of the staff told police.Police officials said that raids were being conducted at various places based on leads from the crime scene.