(CNN)Two explosions at the Jolo Catholic Cathedral in the Mindanao region of the southern Philippines killed more than a dozen people on Sunday.
Two suspected improvised explosive devices (IEDs) detonated in intervals, according to the public relations office for the Autonomous Region of Muslim Mindanao (ARMM).
Initial reports say 17 people are dead and 56 wounded.
The first device went off inside the cathedral, and the second targeted soldiers nearby who rushed to help the victims of the first explosion, Armed Forces of the Philippines spokesman Brigadier General Edgard Arevalo told CNN.
The AFP and the Philippine National Police are securing the area and all casualties were immediately evacuated, ARMM said.
In a statement, Defense Secretary Delfin N. Lorenzana “strongly” condemned the bombing and said he has directed troops to “heighten their alert level” and secure places of worship and public spaces.
“As we convey our sincerest condolences to the families and friends of the victims and offer our sympathy to the peace-loving people of Sulu who are severely affected by this dastardly act, we assure our people that we will use the full force of the law to bring to justice the perpetrators behind this incident,” Lorenzana said.
He urged people to “remain calm and avoid spreading panic in our respective communities to deny terrorism any victory.”
Referendum for peace
The Apostolic Vicariate of Jolo is a Latin Catholic missionary.
The explosion follows a Monday referendum asking the majority-Muslim population whether they back a plan by separatists and the government to create a new self-administered region. The referendum asked to create a new Muslim autonomous region that could bring a peaceful resolution between the government and the rebel group the Moro Islamic Liberation Front –a conflict that has claimed 120,000 lives since the 1970s.
The majority of the 2.8 million people participating in the vote supported the referendum, but the town of Jolo rejected it.
The Philippines Commission on Elections announced on Friday that the referendum was ratified after counting the votes from five provinces.
History of violence
The Mindanao region has been plagued with violence between Muslims and Christians for decades.
It is home to several Islamist insurgent groups, including Abu Sayyaf, which has been blamed for a number of attacks on civilians and Philippine government troops, as well as the kidnapping of several foreign nationals.
As recently as December 31, two people were killed in an explosion outside a busy shopping mall in Cotabato City.
In July, at least 10 people were killed when militants linked to Abu Sayyaf struck a military checkpoint with a car bomb.
Abu Sayyaf — along with the Maute group, another Mindanao-based terror organization — was responsible for the invasion and occupation of Marawi, the country’s biggest Muslim-majority city, in 2017.
The ISIS-affiliated militants laid siege to Marawi for five months, and the violence forced more than 350,000 residents to flee the city and the surrounding areas, as their homes were reduced to rubble by airstrikes and militant fire. In the 150 days of the Philippine army operation to flush the militants out, more than 800 militants and 162 members of the government security forces were killed.