At least 20 people have died in twin bomb attacks on a Roman Catholic cathedral on the island of Jolo in the Southern Philippines.
The Sunday bombing reportedly claimed the lives of five soldiers and 15 civilians, with over 100 people injured in the blasts.
The Islamic State of Iraq and Syria (ISIS) claimed responsibility for the bombings, according to the groups’ Amaq news outlet, which is often the first point of publication for claims of responsibility by the group.
It was initially reported by police that 27 people had died after an incorrect count, but was later revised to 20.
Security officials reported that the initial bomb went off inside or near the Jolo cathedral during Sunday mass, and the second bomb went off in the parking lot while soldiers were responding to the attack.
Defence secretary Delfin Lorenzana said in a statement: “I have directed our troops to heighten their alert level, secure all places of worships and public places at once, and initiate proactive security measures to thwart hostile plans.”
President Rodrigo Duterte and his top security officials are set to visit the province of Sulu on Monday.
Oscar Albayalde, the country’s police chief revealed on Monday that the brother of a slain Abu Sayyaf leader is a suspect in the attack on the cathedral.
Abu Sayyaf, an armed group blacklisted by the United States and the Philippines as a “terrorist organisation” linked to ISIS has been a threat to Jolo for years, and was responsible for the Philippines’ worst terrorist attack, the bombing of Superferry 14 in 2004 which killed 116 people.
Al Jazeera reported the suspect, who the police said is a known bomb-maker, was caught on security camera footage near the church shortly before the attack.
The bombing followed an announcement on Friday that the mainly Muslim region of the predominantly Catholic Philippines, had approved a plan to govern itself by 2022.
The referendum on Monday saw 85% of voters support the creation of an autonomous area called Bangsamoro.
Sulu was one of the only areas that rejected autonomy, but will still form part of the region.