In a major haul, police officials seized about 30kgs of ganja worth Rs 1.5 lakh from a passenger bus at Dudhnoi in Goalpara district on Friday evening.Four people have been arrested in the context. The heavy consignment of drugs were discovered when Dudhnoi police followed a lead by an unknown source and raided the bus AS01-AC-9722 on the National Highway. During the raid, 30 kilos of ganja were retrieved.The four smugglers were identified as Tarok Biswas, Chandan Bhoumik, Soumen Dutta and Gour Mandal and were residents of Navadeep locality in West Bengal. According to reports the men have been smuggling ganja from the state for a long time.Friday's arrest was a result of a tip off received by the police about the possibility of such an attempt. The four smigglers have been kept under police interrogation and are expected to raise the lid of other similar drugs trade in the state.