The attack came less than a month after security guards found an unexploded M-67 grenade inside the GSIS compound, also hurled from outside by motorcycle-riding men.
Tuesday night’s blast shattered the glass panels at the entrance of the GSIS building. No one was reported killed or injured in the explosion.
Senior Superintendent Peraco Macacua, city police chief, said investigators still have no solid clues on the people responsible for the grenade explosion.
Macacua, however, said people complaining about the long-delayed release of salary and policy loans by the GSIS regional office could be behind the attack.
Bai Mamole Pangandaman, GSIS regional manager, earlier said computers used in processing salary and policy loans bogged down when lightning struck a transmission facility, thus stalling the release of benefits to members.
Lately, the GSIS has come under fire when it allegedly released "post-dated" checks for loans.
"This is an indication that something is wrong with the GSIS in Central Mindanao. The National Bureau of Investigation and the Office of the Ombudsman for Mindanao must look into this," said a division chief of a key agency of the Autonomous Region in Muslim Mindanao.
Pangandaman told Catholic radio station dxMS yesterday that their operations would continue despite mounting threats from anonymous quarters.