ISIS has claimed responsibility for the bombing of a church in the Philippines on Sunday in which four people were killed.
Over 50 people were injured in the attack, which took place as a Catholic mass was being held at the Mindanao State University gymnasium in Marawi City.
Marawi is a predominantly Muslim city in the south of the country.
SITE Intelligence Group, which monitors extremist activity online, said that ISIS had claimed responsibility for the attack on the "Christian disbelievers".
Philippines President Ferdinand Marcos Jr condemned the bombing as a "senseless and most heinous" attack and promised to ramp up security in the area.
The attack coincided with the first Sunday in Advent, a period when Christians around the world are reflecting on the coming of Christ into the world and preparing to celebrate his birth on Christmas Day.
It is believed that a grenade or improvised bomb was used in the attack.
It is not the first time that ISIS has been active in the area. In 2017, ISIS militants and government security forces fought for control of the city in a battle that lasted five months and displaced over 350,000 residents.