Emergency services are currently at the daycare centre on Gilles Ave, Newmarket.
A St John spokeswoman said four children were being taken to Starship from Discoveries Educare Newmarket.
She said one of the patients was status one, or critical, one was status two, or serious, and the other two had moderate injuries.
At least two received head injuries, he said.
Emergency services were called at about 1.40pm, he said.
Initial reports indicated that only two children were injured, the number of patients was later increased as was the seriousness of one of their conditions.
The two most seriously injured children had already been taken by ambulance to hospital.
The other children were still inside the centre, where they were being treated by ambulance staff.
Photo / Newstalk ZB
All children were being checked for injuries.
A paramedic was first to arrive on the scene, followed by three ambulances, the police officer said.
Some parents arriving at the scene did not know about what had happened.
There were initial fears other children mightbe trapped by the tree, which fell across play equipment, he said.
“The fire boys checked that though, and there weren’t any. They were awesome.”
A staff member at the daycare centre hung up on a Herald reporter when they called at 2.30pm.
A staff member at the business’ head office said staff had accompanied the children to hospital.
The incident was still unfolding and more information would be made available later this afternoon, she said.
It was understood that the tree may have blown over in the wind. A photo from the scene showed the tree completely uprooted and laying the middle of an outdoor play area.
Childrens toys were visibly crushed and strewn throughout the play area and underneath the tree.
Discoveries Educare owns at least 12 different daycare centres around Auckland.