A Fire and Emergency spokesperson said there were four appliances sent to the scene.
The fire was approximately 35m by 10m and described by the spokesperson as "well involved" when fire crews arrived at the scene.
The spokesperson said all occupants of the building were accounted for and no ambulance had been called.
A witness of the fire who wished to remain anonymous said occupants of the building were alerted to the fire by fire alarms.
"Everybody got out of the building safely," the witness said.
"Staff performed exceptionally to keep everybody safe. The fire service responded quickly."
A police spokeswoman said police were notified of the fire at about 4.30pm by Fire and Emergency services who initially assessed the fire as "suspicious".
Police were on site to help the fire investigator.
Fire crews stayed at Te Manga Place dampening hotspots and left about 6.30pm.