Two of the children drowned in a canal at Charramoni Mohan village around noon while taking a bath.
The deceased were identified as Yasin Arafat, 4, son of Saidul Khokon, and Md. Al-Amin, 5, son of Abdul Asad - both residents of the same village.
Locals rescued them and rushed them to Sadar Hospital, but they died on the way.
In another incident, one-and-a-half-year-old girl Alifa Akhter drowned in a pond in front of her house at Charruhita village around noon.
She was playing near the pond when she suddenly slipped and fell into the water.
Alifa was the daughter of Sohag Hossain of the same village.
Officer-in-Charge of Sadar Police Station Md. Abdul Monnaf confirmed the incidents, reports BSS.