MANILA — The Mindanao State University (MSU) on Tuesday condoled with the families of 4 Mass goers who were killed during a bomb attack in the campus last weekend.

The blast happened on Sunday during a morning Catholic service at MSU's gymnasium in Marawi, the country's largest Muslim city, which was besieged by militant groups in 2017.

In a Facebook post, the university offered "our deepest, sincerest condolences" to the families of the 4 people killed in the explosion, namely, Junrey Barbante, Janine Arenas, Evangeline Aromin, and Riza Daniel.

No other information on the victims was immediately available.

"We pray that your departed loved ones rest in peace and be given the justice they so deserve. We join you in your pain, and to be honest, a part of us, of every MSUan died along with them," MSU System President Basari Mapupuno said, addressing the victims' families.

The Islamic State group has claimed responsibility for the blast from an improvised explosive device.

Before Islamic State claimed the attack, military chief General Romeo Brawner said the bombing might have been a revenge attack for government operations against three Islamist militant groups -- Dawlah Islamiyah-Philippines, Abu Sayyaf and Maute -- in western Mindanao in recent days.

President Ferdinand Marcos Jr. has condemned the attack by "foreign terrorists", describing it as "senseless" and "heinous", while Pope Francis offered his prayers for the victims.

Pro-Islamic State Maute and Abu Sayyaf militants -- including foreign and local fighters -- held Marawi under siege in 2017.

The Philippine military wrested back the ruined city after a five-month battle that claimed more than 1,000 lives.

"There are strong indications of a foreign element (in Sunday's attack)," Defense Secretary Gilbert Teodoro told reporters.

• Foreign terrorist involvement eyed in Marawi blast

— With a report from Agence France-Presse