Military authorities in the region said that it was a homemade explosive device detonated by a mobile phone during a boxing competition, Efe news reported.
The match was part of the celebrations that marked the patron saint festivities in Hilongos city, where the attack took place.
An unspecified number of wounded were being treated for serious injuries.
The Presidential Spokesperson, Ernesto Abella, said that a probe was launched into the attack.
“As of the moment, initial but unofficial news feed state that there were no (intelligence) reports of bomb threats, nor has anybody claimed responsibility for the bombing,” Abella told the media here.
On April 24, during a mass, an unidentified group threw a grenade at a police car parked outside a church in Midsayap city, on the southern island Mindanao, killing 13 people.
Several groups of Muslim radicals operate on Mindanao Island, where majority of the population professes Islam in the otherwise predominantly Catholic country, and demand independence from the Manila Government.