Scene of the Crime Operatives of the Philippine National Police in Valenzuela city, a northern suburb of Manila, Philippines, Thursday, May 14, 2015.

A roadside bomb killed four people in a Filipino politician’s convoy Thursday, while a separate bus blast left a dozen injured in the country’s strife-torn south, authorities said.

The first explosion on Basilan island killed three bodyguards of local official Abdulbaki Ajibon and a fourth person, they said.

Eleven people aboard the two-vehicle convoy were also wounded but Ajibon, the vice mayor of Isabela city, was unhurt, Isabela police chief Superintendent Albert Larubis told reporters.

Investigators said the bomb was planted near the house of the Isabela mayor, Cherrylyn Akbar, though it was unclear which of the two officials were targeted.

The blast destroyed the Ajibon convoy’s backup pickup truck, Larubis added.

No group has claimed responsibility, though Basilan is a stronghold of the Al-Qaeda-linked Abu Sayyaf group, blamed for kidnappings of Westerners as well as deadly bombings.

A bomb also ripped through a bus near the farming town of Polomolok on the same day, some 300 kilometers from Isabela, police said.

Extortionists are suspected of being behind the attack that left 12 people wounded including a seven-year-old girl, said Senior Superintendent Jose Briones, the provincial police director.

Last month, one person was killed and 22 others were wounded in an explosion on another bus in the southern port city of Zamboanga.

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