Five people, including three soldiers, were killed while nine were wounded in an explosion at the gate of a military camp in Sulu on Friday.

Major Arvin Encinas, spokesman of the Western Mindanao Command (Wesmincom), said the explosion happened at the gate of the headquarters of 1st Brigade Combat Team around 12 noon.

"The wounded were promptly given medical attention by the responding troops," he said.

Lt. Col. Ramon Zagala, Philippine Army spokesman, said the explosion occurred at a checkpoint set up by the 1st Brigade Combat Team in its command post in Barangay Kajatian, Indanan.

Zagala said based on an updated report the explosion resulted in the death of three military personnel, two civilians and the wounding of another nine soldiers.

"This attack is meant to disrupt the intensified security operations and our operational tempo following series of recent operational gains in the area," he said.

"We condemn this atrocity which cost the lives of our soldiers whose foremost job is to promote peace in the island," he noted.

"Despite this unfortunate incident, these criminals have failed to deter our troops' resolve and operational verve. We vow to respond with formidable resolve," he added.

Encinas mentioned that the possibility of suicide bombing is "being considered".

He said government forces are still conducting combat and clearing operations in the area.

Major General Cirilito Sobejana, who assumed his post as the new head of the Western Mindanao Command on Zamboanga City, said “ground troops continue to establish the circumstances and identify the perpetrators behind this inhumane attack.”

“We will intensify our offensives to crush terrorist groups that hamper the stability and development in Sulu, ensuring that all actions are in accordance with the law," said Sobejana.

Following the incident, the Western Mindanao Command place all its military camp on heightened alert.

"All the military camps are target of opportunity, if there is such (attack) its our SOP (Standard Operating Procedure) to have our alert status," said Encinas. Robina Asido/DMS