Police forces in Sulu and Basilan were placed under highest security alert in anticipation of the retaliatory attacks from the Abu Sayyaf Group following a joint police and military operation that killed a ranking official of the group and three others in Jolo on Sunday.

"I am tasking the local police units to on full alert because we are expecting retaliatory attacks. We should make sure that the ASG will not be given any opportunity to strike back," said Gen. Guillermo Lorenzo Eleazar, chief of the Philippine National Police (PNP).

State security forces were about to serve a warrant of arrest against Yadah when the Abu Sayyaf terrorists fired at them, prompting the police and the military to retaliate.

Authorities said Yadah was involved in kidnapping incidents while Sawadjaan had knowledge on bomb-making. His brother, Mundi, was the alleged mastermind of the twin blasts in Jolo last year.

Aside from Mundi and Yadah, also killed were a certain Raup and another unidentified ASG member.

“I am tasking the local police to go on full alert dahil ine-expect din po natin na posibleng gumanti ang mga natitirang miyembro lalo’t kapatid ni Mundi Sawadjaan ang isa sa mga napatay sa engkwentro,” PGen Eleazar said.

Eleazar assured that the police and military will further intensify joint operations to capture Mundi and the remaining bandits.

“We are doubling our efforts to capture Mundi and his men. We will intensify our coordination with the Armed Forces of the Philippines as well as our intelligence gathering efforts to combat this group and stop their attacks on innocent civilians,” said Eleazar.

He also urged the public to remain vigilant and immediately report to authorities if they have information that can help locate the bandits.