MANILA, Philippines (Update 6, 10:02 a.m., Jan. 28) — At least 27 people were killed when two bombs hit a cathedral in Jolo, Sulu, the military said Sunday, days after voters backed the creation of a new Muslim autonomous region.

The first explosion occurred inside the Cathedral of Our Lady of Mount Carmel at around 8:15 a.m. when mass was about to begin.

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It was followed by a second explosion at the cathedral's parking area as troops from the 35th Infantry Battalion responded. The Western Mindanao Command said the improvised explosive device was placed inside the utility box of a motorcycle.

The Westmincom said the initial report Sunday morning showed that 17 died due to the explosion while 57 were wounded. As of 12:40 p.m., however, the death toll rose to 27 while 77 people were recorded injured, Autonomous Region in Muslim Mindanao police chief Graciano Mijares said.

ARMM military spokesman Lieutenant Colonel Gerry Besana, however, reported a higher number of 83 people wounded.

Most victims were churchgoers along with five soldiers and a member of the Coast Guard.

The door, pews and glass windows of the cathedral were blown off, military photos showed, with bodies strewn across the ground, according to an Agence France-Presse photographer on the scene.

The Army said it airlifted some of the wounded to the nearby city of Zamboanga for medical treatment.

'Act of terrorism and murder'

President Rodrigo Duterte's spokesman condemned the incident as an "act of terrorism and murder."

"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," presidential spokesman Salvador Panelo said in a statement.

Arevalo assured locals that the Armed Forces is ensuring that medical attention is given to all injured.

"We condemn this dastardly attack on the civilians who were peacefully attending church services at the Jolo Cathedral," Arevalo said in a statement.

Defense Secretary Delfin Lorenzana, meanwhile, announced that the Armed Forces heightened its alert level.

“The Armed Forces of the Philippines has immediately secured the explosion area and transported the casualties to the nearest medical facilities, including the air evacuation of some victims to Zamboanga City for further medication and evaluation,” Lorenzana said.

“I have directed our troops to heighten their alert level, secure all places of worships and public places at once, and initiate pro-active security measures to thwart hostile plans,” Lorenzana added.

Culprit still unknown

The explosions triggered panic among the parishioners and civilians in the vicinity who scampered for safety.

Authorities said the notorious Abu Sayyaf kidnap-for-ransom group could be behind the blasts.

"When you talk about terrorism in Sulu, the primary suspect is always the (Abu Sayyaf) but we are not discounting the possibility that there are other perpetrators," Besana told AFP.

Peace spoilers?

Jolo is a base of the Abu Sayyaf, which is blamed for deadly bombings, including an attack on a ferry in Manila Bay in 2004 that claimed 116 lives in the country's deadliest terror assault.

The Abu Sayyaf is a loose network of militants formed in the 1990s with seed money from Osama bin Laden's Al-Qaeda network, and has earned millions of dollars from banditry and kidnappings-for-ransom, often targetting foreigners.

It is among armed groups based in the strife-torn region of Mindanao, some of whose members have pledged allegiance to the Islamic State group.

Jolo also lies in the proposed Bangsamoro Muslim-majority autonomous region, which local voters overwhelmingly approved last week.

Voters decisively approved a more powerful autonomous region in the Philippines' south, which is hoped will bring peace and development after decades of fighting that have killed thousands and mired the area in poverty.

Sulu province — which includes Jolo — voted against the creation of the new region, with its governor questioning the law establishing the area before the Supreme Court.

Despite Sulu's vote, the legislation provides that the province will still be included in the new political entity as voters from across the current autonomous region voted in favor of it on the whole.

Timing questioned

Sunday's bombing comes after a New Year's Eve blast in Cotabato killed two people and wounded 35 others.

Cotabato last week voted to be included in the new autonomous region.

The timing of Sunday's bombs raised questions on whether the attack was meant to derail the peace process.

Mujiv Hataman, governor of the current autonomous region in Muslim Mindanao, said the blasts highlighted the urgency of implementing the peace law.

"Terrorists want to make their presence known. I hope the (law) is implemented well so it could be a solution to stop the spread of terrorism," Hataman told AFP.

— with reports from Roel Pareño, John Unson and AFP

(Editor's note: An earlier version of this story characterized Sulu as "a stronghold of Islamist militants", a phrase that is unfair to the people of the province and suggests blame even as the official investigation into the bombings is ongoing.)