Police cordon off the finance office of the Harrison Plaza where armed men had earlier ransacked a vault in an early morning robbery. (Photo by HAROLD ORARA)

Heavily armed men robbed the finance department of the Harrison Plaza early Tuesday, police said.

According to Manila Police District (MPD), the robbery happened at around 1:30 a.m. at the second floor of the Harrison Plaza.

The robbers, who wore helmets, face masks, vests and polo shirts ransacked the contents of a vault inside the Velco finance department, investigators said.

The suspects entered the mall using the gate fronting the Century Park Hotel used by construction workers doing renovation work, police said.

Alfaraz Legaspi of the Kemen Security Agency said that he believes the heist was an inside job as the suspects knew where the vault was. The suspects also knew how to disable the closed circuit television (CCTV) cameras inside the mall.

Legaspi told police that the suspects brought him towards the vault and at gunpoint ordered him to open it. The suspects threatened to kill him if he refused, he said.