"The mayor already gave orders to the local police, particularly its chief, Senior Superintendent Roberto Rongavilla, to act on the feud between two groups of vendors, who clashed near a flea market on Montillano street," Muntinlupa public information officer Tez Valencia said.
Rongavilla said the blast took place as Maguindanaon and Maranao vendors were fighting over leadership of the Muslim Vendors Association.
If the vendors do not observe and follow the policies of the local government, local officials would be forced to evict them from the city premises, Valencia said.
She said Fresnedi has continuously enforced security measures in the city "and doesn’t want interruptions or violations in the city’s program on peace and order."
Three hours after the explosion, police were able to arrest one of the suspects in the blast.
Former security guard Samsudih Mokalid, a native of Maguindanao and resident of Signal Village, Taguig, was apprehended inside the Kelly Compound in Alabang after witnesses pointed to him as the one responsible for planting an improvised grenade.
Meanwhile, Southern Police District director Chief Superintendent Wilfredo Garcia said they are conducting follow-up operations to arrest five more suspects, who were tagged as cohorts of Mokalid.
Eighteen people, mostly Muslims, were wounded in the incident.
They were brought to the Ospital ng Muntinlupa for treatment.