The attack came days after a predominantly Muslim area in the region voted "yes" in a referendum for greater autonomy. At least 27 people were killed with scores of more injured, local officials said. Colonel Gerry Besana, spokesman for the Western Mindanao Command, said the first blast killed two civilians and wounded 20 other churchgoers inside the Jolo Cathedral in the province of Sulu  Mr Besana said the second explosive device was detonated as the soldiers responded to the initial attack inside the church, leaving 15 other members of the security forces wounded
The government's plan to create a self-administered area for the Muslim- dominated parts of Mindanao were backed by 85 percent of voters in a referendum last Monday, paving the way for a three-year transition to elections for a legislature that would elect an executive
National police chief Oscar Albayalde said at least
At least 77 others were wounded
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Jolo Island has long been troubled by the presence of Abu Sayyaf militants, who has been blacklisted by the United States and the Philippines as a terrorist organization because of bombings, kidnappings and beheadings
No one immediately claimed
There are terrorist factions in the region, aside from the small but brutal Abu Sayyaf group, which is also aligned with the Islamic State group, which has also carried out assaults, including kidnappings and beheadings. ] Abu Sayyaf militants are still holding at least five hostages ̵
According to unofficial reports, both troops and civilians
Defense Secretary Delfin Lorenzana in a statement: "I have directed our troops to heighten their alert level, secure all places of worship
Photos on social media showing debris and bodies lying on a busy street outside the cathedral as frightened churchgoers scrambled to get to safety
] Rappler reported the local police as saying: "The casualties were immediately evacuated. AFP, PNP (Armed Forces of the Philippines, Philippine National Police) have been securing the area.
They said two improvised explosive devices (IEDs) were used to bomb the cathedral
Last week's referendum came at a critical time for the Philippines, which hopes to end the decades of separatist conflict in Mindanao that experts say has given rise to extremism
That has stoked fears that foreign radicals will gravitate to Mindanao to capitalize on porous borders, jungles and mountains, and an abundance of arms.