Senior Superintendent Sangacala Dampac, city police chief, said the bomb, fashioned from incendiary chemicals rigged with a timing device, was planted in one of the buildings inside the DOTCs Region12 compound in a residential area here.
Dampac said the bomb could have been timed to explode during working hours yesterday, but went off prematurely.
No one was killed or injured in the blast, which shattered glass windows.
Dampac said they are certain that the bombing had something to do with what he described as "administrative differences" between the DOTCs regional director and assistant director.
"One of them has charged the other in the Ombudsman for alleged ghost purchases and ghost deliveries of supplies," he said. John Unson