Four people drowned when a cruise boat carrying 35 to 40 passengers overturned in the Bargi river in Jabalpur district after encountering a sudden storm on Thursday, a police official said.Eighteen people were rescued, while 15 to 18 are still missing, said City Superintendent of Police (Bargi town) Anjul Mishra.Mishra said 35 to 40 people were on the river cruise boat when it overturned because of a sudden storm.Four bodies were recovered from the river, while an operation was on to trace and rescue the missing passengers, said the police officer.