Local investigators identified the victim as Richard Lanzaderas, a finance officer of the DENR-ARMM.
Probers said motorcycle-riding gunmen overtook his vehicle and opened fire with .45 automatic pistols, killing him on the spot.
The victim, along with his subordinate-cashier Jane Trinidad, was driving to the DENR office at the ARMM government center here when the suspects attacked.
Senior Superintendent Ajijul Taradji, city police director, said investigators are now trying to determine the identities of the suspects and their real motive for the attack.
"It could possibly be a robbery attempt because the suspects possibly knew the victim and his companion just came from a bank and were bringing money to their office," Taradji said.
Taradji, however, refused to divulge the amount of money the victim and his companion have have in their possession at the time of the incident.
The suspects reportedly prodded them to open the door of the vehicle, opened fire at Lanzaderas and hurriedly left without taking the money," Taradji said.
The DENR-ARMM has been the subject of criticisms lately for failing to address the mounting complaints of various sectors regarding the wanton cutting of trees in watershed areas in many parts of Maguindanao and Lanao del Sur.
"We have to give our investigators enough time to find out the true angle of this case. In the meantime, we need the cooperation of the witnesses and the officemates of the slain DENR-A RMM official," Taradji said.