Four members of a family were brutally killed at their home in Khalsi village of Helatala union in Satkhira's Kalaroa.
The deceased are- Shahinur Rahman, 40, his wife Sabina Khatun, 30, son Siam Hossain Mahi, 9 and daughter Tasnim, 6.
Shahinur's younger brother Raihanul Islam discovered the bodies on Thursday morning.
According to Raihanul Islam, younger brother of the deceased Shahinur Rahman, they were six people in the family, including him and his mother. On the night of the incident their mother was not at home.
"Early in the morning, I heard the sound of groaning while I was sleeping next door," Raihanul said, adding that, "When I opened the door, which was locked from the outside, the kids were still alive and shortly breathed their last."
Kalaroa Police Station Sub-inspector (SI) Mofizul confirmed the matter and said, "We assume the murders entered into the house using the attic door which was found open."
Police have started investigating the killings.