In a media briefing this morning, Fire and Emergency (FENZ) chief executive Kerry Gregory said a volunteer fire brigade crew had been responding to flooding on Motutara Road on Monday night.
"Last night, just before 11 [pm]... while they were at that incident there was a landslide and the landslide took out two houses and trapped two of our firefighters there," Gregory said.
FENZ and other emergency resources immediately launched a rescue operation, at the site, including ten fire crews from seven brigades, Urban Search and Rescue (USAR) team members, St John ambulance crews, police and defence force staff.
"In what was a really highly technical rescue through there - in the early hours of this morning one of our firefighters was rescued from there and transported to hospital. He's currently in a critical condition in hospital at the moment," Gregory said.
The search for the second firefighter was suspended because of the unstable land, and the rescuers had "grave concerns for the safety of that firefigher", he said.
"The other firefighter that was trapped in the incident ... about 3am this morning, the decision was made that it was too difficult in those conditions to carry on the search for that firefighter, so the search was ceased at that stage.
"It was just too dangerous, the hills were moving, rain was driving in there, the whole street's been evacuated - it was just too dangerous to be in the vicinity let alone on the site itself.
"At the moment they haven't had communication with that firefighter."
Today, firefighters and geotechnical specialists would be at the site.
"We'll make a further assessment today as to whether we can continue the operations around that rescue, or whether that's too dangerous at the moment for our teams - it takes geotechnical specialists to really have a look at that. We certainly don't want to put our crews into a potential - another slip position."
Gregory said they were also very worried about the firefighter who had been freed from the landslide.
"With any crush injury it becomes very risky when a person is released after being trapped after a period of time, so it is a big concern the health of that firefighter."
Support was being provided to the fire crews and families of the firefighters, Gregory said.
"It's been a tough night overnight for the North Island in particular as a whole, but it's been an especially tough night for Fire and Emergency.
"I really feel for all of our organisation and I feel for those families in particular when we've got people right across the country who are just there to support others and help others and find themselves under conditions like this slip when they're just carrying out a routine operation."