A 25-year-old woman and her five-year-old daughter were found dead in the city's Deshipara area on Wednesday night.
The identities of the deceased could not be known immediately.
Police suspect the assailants slit the throats of the mother-daughter duo with sharp weapons. “A probe is on to ascertain the reason behind the killings,” said Ripon.
The bodies were sent to the morgue of Shaheed Tajuddin Ahmed Medical College and Hospital for post-mortem.