A man was killed and five of his relatives were injured on Sunday when a bag picked up in a train supposedly by mistake exploded as soon as it was opened at home.
Officers of the Criminal Investigation Department's bomb disposal squad visited their house and found it had electronic detonators and gelatin sticks.
The incident happened in Rishra, 25 km north of Kolkata, at 10.30am, when Sonu Singh (20), who was killed, opened the bag in the presence of his relatives. Three blasts took place almost immediately and injured five persons.
"Sonu Singh suffered the worst injuries. He was bleeding profusely in his abdomen and was declared brought dead when taken to the Serampore Walsh Hospital," said Afrin Ali, vice-chairman of the Rishra municipality.
Locals said the family had been to Gaya in Bihar on April 30 to attend a wedding. They returned on May 3. Jitendra Singh, Sonu Singh's brother-in-law, and his (Jitendra's) three sons - Bittu (7), Himangshu (6) and Pintu (3) - have been admitted to the hospital. Jitendra Singh's wife, Rekha, too was injured.
While some family members said the bag was picked up in place of the one that belonged to them and looked similar, the police are verifying their statement because there is a discrepancy between the version of Rekha and that of the rest of the family. Her account suggested a co-passenger offered the bag after they had lost theirs.
The police are also checking if this bag bomb had some other target.
"There are various grey areas. We're investigating all aspects," an officer at the Rishra police station said. District superintendent of police Tanmay Roy Choudhury rushed to the spot and spoke to family members.