The group had been in court on various charges relating to violence and driving offences.
The prisoners had been inside Levin District Court and then moved to where a transport vehicle was located inside an internal garage, Stewart said.
One offender pressed an emergency lever to get the roller door open sufficiently for him to escape under.
Another offender then held on to the officer and the other two were able to hold on to him and leave through the garage door.
The trio then ran toward the local supermarket, got into a member of the public's vehicle and made him drive toward northwest Levin, before stopping the vehicle, getting out and fleeing on foot.
The police manhunt is now focusing on Manawatū and further afield.
The group had links in the Horowhenua area with many close associates, she said.
Those associates were warned not to help the men, and to contact police if they got in touch.
Meanwhile it has emerged that one of the trio has previously attempted to escape from prison.
Eparaima has tried to escape prison before, when he and fellow prisoner Jacob Peta tried to break out of Manawatū Prison in 2007, when he was just 18.
The Manawatu Standard reported their escape attempt took over an hour as they climbed four 4m mesh fences.
But they were thwarted at a final perimeter fence when a guard raised the alarm.
Eparaima was sentenced to four months imprisonment to be served cumulatively with his current sentence.
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• Trio escape police custody, on the run in Levin
Levin Police said last night they did not want to unduly concern members of the public, but that anyone who saw suspicious activity should call 111 immediately.
Members of the public were advised not to approach the three men.
"Police are committed to locating and arresting these offenders as quickly as possible and ask for the public's support to do this," police said.
There were reports last night of police stopping and searching cars in Waiterere Beach, looking for the escaped prisoners.
Concerned locals posted to social media that they were triple-checking their locks and would not be answering any doorknocks.
A spokeswoman said police were still trying to find the men at 6am. She did not answer a question about whether the men had been spotted.