A man allegedly killed his wife and minor daughter over a family feud in Domar upazila of the district on Wednesday afternoon.
The accused also stabbed his mother-in-law and threw his 14-day-old baby boy identified as Yasin Islam in a pond during the incident, creating a scene in the area.
Ziarul Islam, 30, also attempted to end his own life by stabbing himself following the incident.
The ill-fated housewife identified as Ratna Begum, 26, and her two-year-old daughter Yasmin Ara, were residents of Pachhim Boragari village in the upazila.
Local people said Ratna along with her husband and children had been staying at her father’s house at Nimojkhana Hartaktala village since before the delivery of son Yasin.
Ziarul, a carpenter by profession, wanted to take his family members away to his house on Wednesday morning and was locked in a quarrel with his wife over the issue.
At one point of the brawl, the unruly Ziarul stabbed his wife and daughter with a sharp knife, leaving them dead on the spot, they said.
The accused also stabbed the mother-in-law while she was trying to save Ratna and Yasmin. Ziarul unbelievably threw his newborn baby in the pond. Yasin is now undergoing treatment at Upazila Health Complex.
Aminul Islam Rimun, chairman of Boragari Union Parishad, said an argument between the couple was settled through arbitration around three months back.
The argument led to the killing, he suspected.
Md Mahmud un-Nabi, Officer-in-charge (OC) of Domar Police Station, said the bodies were sent to Rangpur Medical College Hospital (RMCH) morgue for autopsy.
Ziarul is undergoing treatment at the RMCH while the two others at the Upazila Health Complex, he said adding that no case was yet filed in this connection.