The blast wounded dozens of other Catholic worshippers in the south and sparked a security alarm, including in the capital, Manila, where state forces were put on alert.

The suspected bomb, which the police said was made from a mortar round, went off and hit students and teachers who attended a Mass in a gymnasium at Mindanao State University in Taha Mandangan, the security chief of the state-run campus, told The Associated Press.

Dozens of students and teachers dashed out of the gym as the wounded were taken to hospitals.

Regional military commander Maj Gen Gabriel Viray III said four people were killed by the explosion, including three women. Fifty others were brought to two hospitals for treatment.

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