The Islamic State has claimed responsibility for the bomb attack on a Catholic Mass inside the Mindanao State University in the southern Philippine city of Marawi on Sunday (December 3) that killed at least four people and injured 50 others.

In a statement on its Telegram channel, the terrorist group said that its operatives "detonated an explosive device on a large gathering of Christians... in the city of Marawi."

Philippine security officials earlier said the blast from an improvised explosive device might have been a retaliatory attack for a series of military operations against Islamist militant groups in recent days.

However, Bangsamoro regional police public information officer Lt. Eirene Mazon told Filipino broadcaster ABS-CBN that investigators were "still gathering information" on the Islamic State claim.

"We are accepting all the possibilities," she said. "As of now, we have persons of interest and we are also looking at several angles about the cause of this incident."

(Photo: MERLYN MANOS/AFP via Getty Images)

Police in the Muslim-majority Bangsamoro region are now tasked with hunting down at least two suspects connected to the attack.

Earlier, Washington officials have also condemned the incident, calling it a "horrific" attack on Christians inside a Muslim city. Japan, Australia, Britain, China, and Canada have also voiced their condemnation of the incident.

Read Also: Philippines: At Least 4 Dead in Explosion During Catholic Mass in Marawi

Pope Francis Prays for Victims of Marawi Bomb Attack

In his Sunday Angelus address, Pope Francis urged the congregation gathered in St. Peter's Square in Rome to pray for the victims of the bombing attack in Marawi.

"I would like to assure you of my prayers for the victims of the attack in the Philippines this morning, where a bomb exploded during Mass," he said.

In the hours since the attack, the Vatican sent a telegram to the territorial prelate of Marawi, Bishop Edwin de la Peña.

The message, signed by Vatican Secretary of State Cardinal Pietro Parolin told the bishop that the Holy See was "saddened" with the injuries and loss of life caused by the bomb attack. Cardinal Parolin added that Francis had asked de la Peña "to convey his spiritual closeness" to the victims.

Separately, the pope posted on X, the social media platform formerly known as Twitter, that he would be praying for those who were affected by the bombing.

Meanwhile, Manila Archbishop Cardinal Jose Advincula said the killing of innocent Christians in Marawi was ironic as it happened merely days after "Red Wednesday," a commemoration held by the Catholic Church every last Wednesday of November to remember Christians persecuted, harmed, or killed for their faith.

Related Article: Marawi Terrorist Bombing of MSU Catholic Mass Condemned by US Govt.