Police said floodwater began collecting at the base of a 10-foot wall separating the squatters area from Ideal Subdivision in Barangay Commonwealth.
The wall collapsed on the shanty of the Sibelo family, trapping people inside as the floodwater started rushing toward them.
John Lloyd Sibelo, 4, was swept by the rushing water and drowned.
He was brought to the FEU Hospital in Fairview, but was declared dead on arrival by the attending doctor.
The boys mother, Marivic; his siblings Junel, 7, Michael, 13, and Thomy, 12; and relatives Christy, 18, and Ryza, 1, sustained cuts and scratches.
Some of them also suffered electric shock from a live wire that touched the floodwater. Katherine Adraneda