While escaping an hour later, the robbers opened fire at and wounded a couple riding tandem on a motorcycle they chanced upon in the middle of the street.
Senior Superintendent Freddie Panen, Rizal police director, has dispatched a crack team to track down the robbers, described as between 20 and 25 years old and sporting crewcut hair.
The police said the robbers rushed inside the house in Barangay San Jose after the homeowners opened the door at about 2 a.m.
Armed with handguns, the robbers herded the homeowners, the two teenagers and their grandmother in the sala before ransacking the house of cash and valuables.
At gunpoint, they then dragged the twins into a room where they took turns sexually molesting them.
The robbers escaped on board the houseowner’s Kia Pride.
When they reached F. Samonte street in Barangay San Juan, the robbers chanced upon Alexander Doming, 28, and his girlfriend, Karen Bayaga, on board a motorcycle.
Then they opened fire at the unsuspecting duo, hitting Doming in the chest and buttocks and Bayaga in the leg.
Doming and Bayaga were rushed to the Manila East Medical Hospital.
Panen said the robbers left behind a magazine for a 9-mm pistol loaded with 13 live bullets and a white cap with the marking "Duke Girls" at the ransacked residence.
The police recovered the homeowners’ vehicle a few meters away from where the robbers shot Doming and Bayaga.