The explosion during Sunday morning Mass at Mindanao State University in Marawi City was not a suicide bombing, Lanao del Sur Gov. Mamintal Alonto Adiong Jr. said Monday.

• Explosion at Catholic Mass kills 4 in southern Philippines

Speaking to TeleRadyo Serbisyo, Adiong said all 4 fatalities in Sunday's explosion have been identified.

"Ngayong umaga, identified na 'yung isa sa namatay, nasa [Philippine National Police] na. Kagabi wala pa kasi walang makapagsabi kasi hindi klaro, nung masabugan siya hindi na maklaro 'yung itsura niya."

"Hindi (suicide bombing)," he said, adding police have yet to identify a suspect.

• Foreign terrorist involvement eyed in Marawi blast

Police earlier said they found fragments of a 60mm mortar from the improvised bomb used in the attack.

Adiong said 35 out of 47 people injured that were admitted to Amai Pakpak Medical Center after the explosion were discharged Sunday. Some of those discharged were allowed to go home while others were brought to the MSU infirmary.

At least 2 patients at Amai Pakpak are in critical condition and needed surgery.

The governor said MSU officials have decided to push through with exams this week after police and military officials vowed to send augmentation troops to the university.

Adiong said a motive for the crime has yet to be established.

"Hanggang ngayon hindi ko pa rin alam, dahil matagal na, magmula nung Marawi siege, ngayon pa lang nagkaroon ng ganito dito sa amin, itinaon pa sa Mass ng ating mga kapatid na Kristiyano," he said.

• MSU church service bombing could be 'retaliatory attack': AFP