Nineteen other passengers swam to safety, Sub-Divisional Officer (SDO) Kundan Kumar said.
The mishap took place near Babua Ghat when the boat carrying 24 flood-affected people from Sitacharan riverine area lost control and capsized in the river apparently after some cattle on board got frightened and moved in wayward manner creating panic among the passengers, Kumar said.
While a one-year-old boy, identified as Ajit, drowned, four others, including two women were feared drowned.