A visiting Saudi Muslim cleric and a Saudi Arabian diplomat were shot and wounded in the southern city of Zamboanga on March 1.
Police identified the victims as Ayed Al-Qarni, an international lecturer and author of Islamic books, and Sheikh Turki Assaegh, religious attache at the Saudi Arabian embassy in Manila.
Gunmen shot the victims who were leaving Western Mindanao State University where Al-Qarni delivered a lecture earlier in the day. One assailant was killed in an exchange of gunfire with security personnel, while two other people thought to be with him were arrested.
Al-Qarni and Assaegh were later flown to Manila for treatment where they were declared out of danger.
“We are still investigating the motive for the attack,” said police spokeswoman Helen Galvez.
Al-Qarni has been on the U.S. no-fly list and had been barred from attending a conference in Chicago in 2012.
The author was also reported to be the target of the so-called Islamic State for criticizing the group.
The attack on Al-Qarni came hours after the Philippine military announced that it has neutralized an Islamist group that has earlier pledged allegiance to Islamic State in the province of Lanao del Sur.