Police identified the victims as Webb Santos, 40, and his wife Alma, 35; Darmo Rivera, 20; Roberto Talagtag and John Michael Gardose, both 18; and Judy Ann Severo and Joshua Tuazon, both 16 years old.
The victims were reportedly among those relocated from Tondo, Manila to a government site in Barangay San Jose, Rodriguez.
Senior Supt. Rolando Anduyan, Rizal police director, said they are initially looking into a case of double-cross.
Anduyan said that the Santos couple, who owned the house where the victims were shot dead, was on the police watch-list for illegal drug trade.
“According to their neighbors, the victims were drinking while having a pot session before the shooting happened,” Anduyan said, although the police failed to recover illegal drugs from the house.
He however said it was not yet clear if the assailants, at least four people, barged into the house or were drinking with the victims before the shooting, which erupted at around 1 a.m.
Anduyan said they were also going to run tests on the victims for gun powder. The police said they found no weapon inside the house.