
They had initially thought the elderly couple and their two grandsons were killed in the fire.
However, their view changed after stab wounds were detected on three of the bodies, said Selangor Criminal Investigation Department chief SAC Fadzil Ahmat.
The couple were identified as Chia Tee Nang, 73, and his wife Lim Mai Shak, 68. Their grandsons Chia Yuan Bin, three, and Ryan Chia, nine, were cousins.
The fire destroyed the single-storey wooden house on Jalan Tepi Laut.
Fadzil said police were informed of the incident at 5.50am.
It is learned that another grandson, aged 12, managed to escape from the house and was taken to hospital.