The reports said that Burun Chakma, a resident of Diblibagh near Tlabung town and his two sons - Aisa (5) and Ojon (one and half years old) were drowned in the river on Saturday.
Their bodies were yet to be recovered.
The boat in which Barun Chakma was aboard with his wife Santi, two sons and two sons-in-law carrying husked rice weighing around 30 kg, capsized in the strong current.
His wife and two sons-in-law managed to swim across with the help of some people.
Young Chakma Association (YCA) asked the villagers in the down stream to join in the rescue work as the strong current of the water was making it difficult for the volunteers.