THE NATIONAL Bureau of Investigation (NBI) has started investigating the recent bus bombings in southern Philippines, as it tries to prevent the terror acts from spilling into Manila, the capital, it said in a statement on Wednesday evening.

“The bureau’s probe on the series of bombings is directed at ensuring national security as well as preventing possible major attacks not only in Mindanao but also in the entire country,” it said. “Extortion and terrorism are the motives of the bombing based on information gathered.”

NBI Officer-in-Charge Eric B. Distor, the bureau’s counter-terrorism division and a forensics team have traveled to Mindanao for the probe.

There have been six bombing incidents on bus lines in the region in the past two years, with four happening this year, NBI said.

The first of the bus bombings this year took place on Jan. 11 in the town of Aleosan, North Cotabato, killing a five-year-old boy and wounding three others. On April 24, a bus exploded in Parang, Maguindanao, injuring at least three passengers.

The most recent bombings happened on May 26 in Koronadal City, South Cotabato, hurting two civilians. The NBI also cited a separate roadside bombing on the same day in Tacurong, Sultan Kudarat.

The series of bombings started on Jan. 7 last year, when a local bus operator in Koronadal City received a bomb threat call and an extortion demand from an anonymous caller.

Local police found an improvised explosive device inside one of the buses. CCTV footage showed two male passengers leaving the device inside the bus.

Another attack took place on June 3 last year when a bus was burned in the town of M’lang, North Cotabato, killing three and wounding six other people.

Last week, a suspect in the bombing incidents was killed in a clash with police and military troops in M’lang, according to the Armed Forces of the Philippines.

The suspect was identified as a member of the Dawlah Islamiyah terrorist group in Maguindanao province. — John Victor D. Ordoñez