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Military personnel look at debris from the explosion scene inside a church on the island of Jolo in Sulu Province, the Philippines, Jan. 27, 2019. Twenty people, including five army soldiers, were killed and 111 others wounded on Sunday as two blasts went off inside and near the entrance of a Roman Catholic church on the island of Jolo in the southern Philippine province of Sulu, police said. (Xinhua/Stringer)

MANILA, Jan. 27 (Xinhua) -- Twenty people were killed and 111 others wounded on Sunday as two blasts went off inside and near the entrance of a Roman Catholic church on the island of Jolo in the southern Philippine province of Sulu, police said.

"Hopefully the number of those killed in the incident will stop at 20," Police Chief Superintendent Graciano Mijares, Philippine National Police (PNP) director in the Autonomous Region in Muslim Mindanao, told Xinhua over phone.

Mijares said earlier that 27 were killed in the incident, which took place at around 8:28 a.m. (0028 GMT) on Sunday.

"As of this time, data (are) being reconciled and victims are being identified. There were double entries in the tally of the incident command post this morning regarding data of killed victims," Mijares said in a report.

Many of the injured were taken to local hospitals in Jolo. At least seven of the critically wounded were helicoptered to Zamboanga City, he said.

Among the 20 dead, 14 were civilians, five were members of the Armed Forces of the Philippines (AFP) and one was member of the Philippine Coast Guard (PCG), according to Mijares.

Among the 111 wounded, 90 were civilians, 17 were AFP members, two were PCG members and two were policemen.

PNP chief Director General Oscar Albayalde said the bombs are believed to be an improvised explosive device (IED). He said one IED went off inside the church while the other went off outside, near the entrance of the church. "It went off one minute apart," he said.

Col. Gerry Besana, spokesman of the military's Western Mindanao Command based in Zamboanga City, said one IED exploded inside the church while a mass was underway. A couple of minutes later, another IED exploded in front of the church killing the soldiers who swiftly responded to the first blast, he said.

Besana said the IED was placed inside the utility box of a motorcycle parked outside the church.

No group has claimed responsibility for the attack so far.

The attack took place seven days after residents of predominantly-Muslim provinces ratified in a plebiscite the Bangsamoro Organic Law (BOL).

The law was expected to pave the way for the creation of a wider autonomous region for Muslim Filipinos in Mindanao called Bangsamoro Autonomous Region of Muslim Mindanao (BARMM), and usher in peace in the conflict-plagued southern region.

Presidential spokesman Salvador Panelo said authorities "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 Armed Forces of the Philippines will rise to the challenge and crush the godless criminals," Panelo said.

Presidential Peace Adviser Carlito Galvez urged people in Mindanao "not to cower and be intimidated by such a selfish and cowardly deed."

Philippine Defense Secretary Delfin Lorenzana said he had directed troops to heighten alert level, secure all places of worships and public places at once, and initiate pro-active security measures to thwart hostile plans.

Lorenzana urged the public to be more vigilant and to be cooperative with the authorities in reporting any security related concerns.

"We also urge everyone to remain calm and avoid spreading panic in our respective communities to deny terrorism any victory," Lorenzana said.

Meanwhile, National Security Adviser Hermogenes Esperon said "security forces have tightened up the systems to secure Sulu and the rest of BARMM."

Jolo is the base for Abu Sayyaf militant group, which has recently become better known for criminal brutality, kidnaping-for-ransom activities, bombings, and beheadings in western Mindanao, particularly in their lair in the island provinces of Basilan and Sulu. The group is smallest but also the most radical of Islamist groups in the Philippines.

Last month the AFP created an Army infantry division that will mainly hunt down the elusive Abu Sayyaf terrorists in Sulu province.

The attack took place while Mindanao is under martial rule.