Commissioner Taitosauā Edward Winterstein said inmates ambushed the prison guards and assaulted them, leaving one in a critical condition.
Mr Winterstein told a news conference the five guards were overpowered by 36 inmates.
Earlier, it was reported that 29 had escaped but the news conference was told it was 36.
The guards received a range of injuries, and were treated at the Motootua hospital.
The prisoners then damaged the administration block, switched off communications and the power supply, and fled into the night.
Most have been recaptured, but four - including a man imprisoned for double murder - are still on the run.
The police are investigating the breakout, and the prime minister said the police ministry would now take over the running of the country's prisons.
Since it opened a year ago, the brand new Tanumalala prison has seen several escapes.
Photo RNZ Pacific