MANILA, Philippines (AP) — An explosion wounded at least 23 people who were watching a boxing competition held as part of celebrations of an annual Roman Catholic festival in a central Philippine town, an army officer said.

The wounded were brought to a hospital in Hilongos town in Leyte province following the explosion late Wednesday of what initially appeared to be a cellphone-detonated homemade bomb, regional army spokeswoman 1st Lt. Cherry Junia said.

Nobody has claimed responsibility for the attack.

Leyte province, about 610 kilometers (380 miles) southeast of Manila, lies in a region where communist guerrillas have a presence, but there was no immediate indication they were involved.

Philippine forces also have been placed on alert amid on and off offensives against Muslim militants in the country's south.