Two brothers, their wives and their three children were found murdered yesterday in their double-storey rented house in the densely-populated area of Jauhar Town.
A third brother who was unmarried and also found dead is suspected to be the murderer.
The victims are Shahid Iqbal, 43, his wife Farzana, 41, and their children - Afaq, 13, and Amna, 8; Zahid Iqbal, 50, his wife Naseem, 45, and daughter Areeba, 6.
Nazir Ahmed, 55, the brother of Shahid and Zahid, is suspected to be the murderer.
More From This Section
A police investigator said, "Nazir, a chemical engineer by profession, was found dead with no bruises on his body suggesting he killed his other family members before committing suicide."
The seven victims were administered tranquillisers before their heads were crushed with a hammer, a forensic official said.
"However, there is no injury mark on the body of Nazir. Nazir was a cancer patient and unmarried. We are suspecting Nazir's involvement in the killings," the investigator said.
The dead bodies were shifted to their native town Gujranwala, some 80 kilometres from here, for burial.
Police are investigating all aspects of the case.