(CNN) Two bombs tore through a Roman Catholic cathedral in southern Philippines on Sunday, killing at least 20 people and leaving dozens wounded, authorities said.

Two suspected improvised explosive devices detonated at intervals at the Jolo Catholic cathedral in the Mindanao region, according to the Autonomous Region of Muslim Mindanao. At least 81 people have been wounded, authorities said, including 14 soldiers of the Armed Forces of the Philippines and two Philippine National Police officers.

The first device went off inside the cathedral, and the second one targeted nearby soldiers who rushed to help the victims of the first explosion, Armed Forces of the Philippines spokesman Brig. Gen. Edgard Arevalo said.

ISIS on Sunday claimed responsibility for the bombings via its Amaq News Agency. Shortly after the Amaq report, ISIS' "East Asia Province" also issued a formal communique for the twin suicide bombings.

ISIS did not provide evidence for its claim, nor can CNN independently verify it.

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