Police and ambulance search and rescue staff made their way by 4WD to the southern end of Karekare Beach, before calling for the rescue helicopter at 8pm.
They spotted the group while flying along the coast at 8.30pm, Mr Knight said.
"We could see headlamps and torchlights at the base of these big cliffs."
Paramedic Chris Deacon was winched to the group and decided to winch the two 16-year-olds to the helicopter.
Two search and rescue staff were left with the remaining trampers, and by 11pm all had been walked out of the bush to Karekare Beach unharmed.
Police said the group were in good spirits and spent the night in Karekare.
A Karekare resident said the group entered an area known as the Pararaha - a swampy marshland about 40 minutes walk from the main Karekare Beach.
Karekare children visited there all the time, but for "city kids" it could have seemed a treacherous wilderness, the resident said.
"There's a bit of a swamp down there at the Pararaha. But for folk like ourselves it's actually pretty tame. Obviously, because it took a bit longer than they expected and it got a bit dark they freaked out a bit. But they were actually not very far from civilisation."
Residents with quad bikes joined in the search and helped bring back the rest of the group.
The Auckland Council park's website says Muir Track is recommended for experienced trampers. It is steep and in some places requires clambering around rock-faces and banks.
Meanwhile, in a second incident a 17-year-old girl who was part of a six-person group tramping on the Twin Peak Track received hip and knee injuries yesterday.
Search and rescue are currently escorting the girl out of the Waitakere ranges.
Police said her tramping party was well equipped with tents and camping equipment and she was in comfortable condition as the group set up camp last night.
About 10.18am, SAR staff reached the tramping party and are currently in the process of walking the teen and the rest of the group out of the ranges.
Police will provide an update when all involved safely make it out.