«I condemn in the strongest possible terms the senseless and most heinous acts perpetrated by foreign terrorists,» said President Ferdinand Marcos Jr. «Extremists who wield violence against the innocent will always be regarded as enemies to our society.»
The blast in Marawi, a city besieged by pro-Islamic State militants for five months in 2017, followed the killing of 11 combatants in a military operation on Friday in Maguindanao del Sur some 200 km (125 miles) away.
Urging calm, Marcos posted on the social media platform X that he had instructed the national police and armed forces «to ensure the protection and safety of civilians and the security of affected and vulnerable communities».
«Rest assured we will bring the perpetrators of this ruthless act to justice.»
Army Major General Gabriel Viray III called the attack at the Mindanao State University «a terror act», speaking to reporters as explosive disposal experts were deployed.
«Right now we are on heightened alert and our troops remain vigilant as we are determining the motive and identifying the perpetrators to really ascertain who was behind it,» Viray said.
Military officials surveyed the gymnasium, which appeared intact except for burn marks in the centre where the explosion occurred, according to images shared by the government of Lanao del Sur on its Facebook account. White plastic chairs were strewn about.