MANILA, Philippines (AP) -- President Rodrigo Duterte and his top security officials on Monday visited a Catholic cathedral in the southern Philippines where suspected Islamic militants set off bombs that killed at least 20 people and wounded more than 100.
The first blast sent people, some of them wounded, fleeing out the church's main door. Army troops and police were rushing inside when the second bomb exploded a minute later. The explosions scattered wooden pews inside the main hall, blasted out window glass panels and hurled human remains and debris across a town square fronting the Cathedral of Our Lady of Mount Carmel, witnesses said.
The attack occurred in the Sulu provincial capital on Jolo island, where Abu Sayyaf militants have carried out years of bombings, kidnappings and beheadings and have aligned themselves with the Islamic State group, which claimed responsibility for the attack.
Duterte met with some of the survivors and held a security meeting with military and police officials. Police have put forces around the country on heightened alert to prevent similar attacks.
"We will pursue to the ends of the earth the ruthless perpetrators behind this dastardly crime until every killer is brought to justice and put behind bars. The law will give them no mercy," the president's office said earlier.
The bombings came nearly a week after minority Muslims in the predominantly Roman Catholic nation endorsed a new autonomous region in the southern Philippines in hopes of ending nearly five decades of a separatist rebellion that has left 150,000 people dead. Although most Muslim areas approved the autonomy deal, voters in Sulu province, where Jolo is located, rejected it. The province is home to a rival rebel faction that's opposed to the deal as well as smaller militant cells that are not part of any peace process.
A top Philippine government official told The Associated Press that an Abu Sayyaf commander, Hatib Sawadjaan, is one of the main suspects. At least four of Sawadjaan's men were filmed by security cameras near the bombed area, said the official, who spoke on condition of anonymity to discuss the investigation.
Sawadjaan is based in the jungles of Patikul town, near Jolo, and has been blamed for kidnappings for ransom and beheadings of hostages, including two Canadian men, in recent years. Sawadjaan's faction has aired ransom-demanding videos that used Islamic State-styled black flags as backdrops.
A statement by the Islamic State group posted on social media claimed the attack was carried out by two suicide bombers who wore explosive belts, one detonating at the gate and the other in the parking lot.
Police said at least 20 people died and 111 were wounded. The fatalities were 15 civilians and five troops. Among the wounded, about 90 are civilians.
The United Nations and others denounced the attack. In a statement attributed to a spokesman, Secretary-General Antonio Guterres called for the perpetrators to be brought to justice and reiterated the U.N.'s support for the Philippines' efforts to fight terrorism and to carry forward a peace process in the Muslim region.
Western governments welcomed the autonomy pact in part to ease concerns that Filipino militants could ally themselves with foreigners and turn the southern region into a breeding ground for extremists.
Aside from Abu Sayyaf, other militant groups in Sulu include a small band of young jihadis aligned with the Islamic State group.
Government forces have pressed on sporadic offensives to crush the militants, and Duterte has extended martial law in the entire southern third of the country to allow troops to finish off radical Muslim groups and other insurgents, but bombings and other attacks have continued.