Blast injures 7 presidential guards in Philippines
PSG spokesman Lt. Colonel Michael Aquino said the explosion took place around 10.45 a.m. (local time), and seriously wounded one person, Efe news reported.
Aquino added the blast was being probed but said it was yet to be ascertained if the attack was directed at President Rodrigo Duterte or was linked with clashes between the military and Maute Group Islamist rebels.
The seven injured PSG personnel were part of a delegation of 50 persons who were visiting Lanao del Sur to organise Duterte's visit.
Duterte's visit on Wednesday was meant to show support to the personnel fighting the jihadists.
The Philippine Armed Forces since November 26 were clashing with the Maute Group that laid siege to Butig. The clash left 35 rebels dead and 13 soldiers injured.
Authorities suspect the same insurgent group was also responsible for the bomb recovered from near the US embassy in Manila on Monday.
Maute Group is an armed Muslim organisation based in Lanao del Sur, which emerged on the national stage in 2012 with the name Khilafah Islamiyah Movement (KIM).
According to the Institute for Policy Analysis of Conflict, KIM is currently led by brothers Omar and Abdullah Maute Romato.