The preliminary post-mortem report has indicated that a mother and her three children, whose bodies were found in Lahore's Valencia Town, died from suspected poisoning, 24NewsHD TV reported on Saturday.
According to the initial autopsy findings, the deaths were caused by poisoning.
Vomit residue was found on the clothes of two of the children, further supporting the possibility of toxic substance ingestion.
Police said it is too early to determine whether the victims were deliberately poisoned or died after consuming a poisonous substance.
Officials stressed that the exact cause and manner of death will only be confirmed after the final forensic and chemical examination reports are received.
The post-mortem examination has been completed, and the bodies have been handed over to the police for further legal proceedings.
Earlier, the children's father, Nasir, told investigators that his wife had been suffering from severe mental stress and psychological illness for the past three years and had stopped taking her prescribed medication about six months ago.
He expressed concern that, due to her mental condition, she may have mixed something into ice cream and given it to the children. However, police have not confirmed this claim and say all possibilities are being thoroughly investigated.
Police officials described the case as highly complex, adding that investigators are examining every aspect before reaching any conclusions.
The incident came to light on Friday when the bodies of three children were recovered from their home in Valencia Town, while their mother later died at a hospital.
The investigation remained underway pending the final forensic report.