After alighting from a bus, the couple went to an isolated area near the Abu bus stand and consumed poison.
They also administered it to their six-year-old girl.
They were later spotted lying in an unconscious state and the police were informed.
The three were rushed to a nearby hospital where the woman, aged around 35 years, and the girl, died on arrival, police said, adding that the man is undergoing treatment.
Efforts are being made ascertain their identity, they added.
