A case was filed in connection with the killing of three people including two children in Goainghat upazila of Sylhet district.
Father of slain Alema filed the case with Goainghat Police Station early Thursday, said officer-in-charge of the police station Abdul Ahad.
Earlier on Wednesday, three people including two minor children were found dead at a house at Binnakandi South para in the upazila.
The deceased were identified as Alema, 30, wife of Hifzur Rahman and her two children—Mizan 8, and Anisa, 3. Hifzur was found wounded during the incident.
Hifzur is now undergoing treatment at Sylhet Osmani Medical College and Hospital under police custody.
According to the local people, miscreants swooped on the house sometime in the night and stabbed Alema to death and killed the two babies after slitting their throats.
They also hit Hifzur with sharp weapons, leaving him injured.
Police suspected that miscreants carried out the attack over previous enmity.