The grenade attack on the house of Tony Domes-ag did not hurt anyone but damaged three vehicles.
Domes-ag is pitted against his own wife, Lovelyn Domes-ag, and retired police colonel Wilmer Panabang. It is not known if the Domes-ags are legally separated.
Panabang was surprised when reporters tried to get his comment on the incident, saying he was in Pangasinan when it happened.
"I just learned from you about this," he said. "If the elections were held today, I can easily defeat my two opponents."
Senior Superintendent Artemio Hicban, provincial police director, said they were probing how the grenade attack occurred considering that Domes-ags house was guarded.
Last week, Lito Bigornia, president of the Association of Barangay Captains in the capital town of Bangued, was shot and seriously wounded.
Bigornia has been transferred to a hospital in Manila for the treatment of his five bullet wounds from a caliber .45 pistol.
Bigornia is a brother of Jowel Bigornia, vice mayoral running mate of re-electionist Bangued Mayor Ma. Cita Claustro-Valera.
Escalating violence believed to be politically motivated has prompted the police to recommend that four towns Bangued, Lagayan, Lagangilang and Tineg be placed under the control of the Commission on Elections.