The explosion occurred in front of a clothing stall along a highway in Isulan in Sultan Kudarat province, where a festival was taking place.
An investigation was underway and there were no immediate claims of responsibility, according to police.
The province is on the Philippines` second-largest island,
Mindanao, parts of which have been plagued by decades of Maoist and separatist rebellions that have given rise to banditry and the influence of the Islamic State group.
Arvin Encinas, spokesman of the army`s 6th Infantry Division, said the Bangsamoro Islamic Freedom Fighters (BIFF), an armed group that has pledged allegiance with Islamic State, was suspected of being behind the attack.
Mindanao remains under martial law until the end of the year following a five-month occupation Marawi City in 2017 by an alliance of rebels loyal to Islamic State, in which the military prevailed. Hundreds of people were killed, mostly rebels and soldiers.
The latest bombing comes a month after a device was detonated in a van stopped at a checkpoint on the island of Basilan which killed 11 people, including four civilians.
Editing by Mohammad Anthony, Boyke Soekapdjo
Reporter: antara
Editor: Heru Purwanto
Copyright © ANTARA 2018
