At least four persons including a child were killed and seven others went missing after a boat carrying at least 29 passengers capsized in Chilika lagoon in Odisha's Ganjam district on Saturday, officials said.Ganjam Collector Prem Chandra Choudhury said four persons died in the incident while the rescue operation was on to trace the other seven persons.He said most of the passengers have been rescued and admitted to MKCG Medical College and Hospital, Berhampur and at Rambha hospital."Efforts are on to rescue the missing persons. The Fire Brigade team and the people of the locality are trying to trace out seven missing passengers," he said.The persons were travelling from Sabalia to Ghantisila in the overloaded boat.Following the accident, the locals rushed to the spot and managed to rescue several persons. Expressing grief over the incident, Chief Minister Naveen Patnaik announced ex gratia of Rs 4 lakh to each family of the deceased.He also directed to expedite the rescue operation and treatment of all injured passengers.