Senior Superintendent Roberto Rongavilla said one of the victims was in serious condition after losing an arm in the blast in Muntinlupa City, but the others suffered only minor injuries.
"It appears grudge is the motive, because one of the victims – the one who lost an arm-filed a case against the suspect," Rongavilla said in a TV interview.
He said the suspect is being hunted down by the police.
Rongavilla ruled out the possibility of terrorist involvement in the blast.