The Islamic State announced on Telegram that its members detonated the device that caused the explosion, news agencies reported.
“Extremists who wield violence against the innocent will always be regarded as enemies to our society,” the president said.
The island of Mindanao in the southern Philippines, which includes a Muslim-majority autonomous region, has historically been wracked with armed conflict, and insurgent groups remain active in some areas.
On Sunday, photos and videos of the scene showed bodies and plastic chairs strewn across the gym floor. Survivors emerged with scrapes and blood-soaked clothes.
Pope Francis said Sunday that he prayed for the victims of the attack. “I am close to the families and the people of Mindanao, who have already suffered so much,” he said on social media.
In a Facebook group for the university community, users expressed solidarity, but also fear. “To our Christian sisters, if you go out later … wear a hijab,” one comment with over 40 reactions read. “We just want to ensure you are safe.”
Mamintal Alonto Adiong Jr., governor of Lanao del Sur in Mindanao, said the province upholds “basic human rights, and that includes the right to religion.”
Diplomats from the United States, Canada, Britain and the European Union condemned the attack. “I extend deepest condolences on the part of the U.S. government,” U.S. ambassador to the Philippines MaryKay Carlson said on social media.
The university has suspended classes until further notice. “We stand in solidarity with our Christian community and all those affected by this tragedy,” it said in a statement.
An initial investigation found “the bomb signature is probably from Daula Islamiyah Maute Group,” said Philippine army spokesman Louie Dema-ala, but authorities were reviewing other possibilities.
The Maute group — which is affiliated with the Islamic State terrorist organization — is among the militant groups that besieged Marawi City for five months in 2017. Those Islamist forces included foreign fighters from countries such as Malaysia and Yemen.
In 2019, authorities traced the suicide bombing of a cathedral in Mindanao to an Indonesian couple.
Westfall reported from Washington.