An improvised bomb exploded Saturday at the roof of a Catholic church in the southern Philippines, injuring six people attending a Christmas Day mass, a regional military spokesman said.

Among those wounded was the priest who was celebrating the mass at the chapel of a police camp on Jolo Island, 1,000 km south of Manila, Lieutenant Colonel Randolph Cabangbang said.

Cabangbang said the bomb was placed at the rooftop of the chapel, damaging the steel beam and the ceiling during the blast.

Police have not yet determined the suspects behind the attack, but Jolo is a known lair of the Al Qaeda-linked Abu Sayyaf rebels, who have been blamed for deadly terrorist attacks in the Philippines.

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