UPDATED 8.11pm The conditions of the two toddlers most seriously hurt when a large tree toppled on a kids' play area in Auckland this afternoon have improved.

Both children were taken by ambulance to Starship Hospital, with one listed as critical and the other serious, along with a third child with moderate injuries. A fourth child, who suffered minor injuries, was also taken to Starship by its parents.

An Auckland District Health Board spokeswoman confirmed this evening the two worst hurt children were in stable conditions.

She did not have further information, but confirmed the update meant the condition of both children had improved.

There was no information on the two other children, indicating neither had been admitted, she said.

The dramatic incident unfolded at Discoveries Educare in the Auckland suburb of Newmarket just after 1.30pm today, and left parents facing their worst nightmare.

Parents of four children were told their children had been hurt when the tree toppled into a playground crowded with 25 of the 47 or 48 children enrolled at the daycare.

The tree struck a playhouse and kids' toys lay scattered around the area after the uninjured children were ushered inside, checked and given afternoon tea to calm any fears.

A manager at the daycare, which employs about 10 staff, travelled to hospital with the injured children, while ambulance crews inside checked all children who were outside when the tree fell.

t John Ambulance Auckland central territory manager Simon Barnett said parents were given information on concussion symptoms and what to do if they became concerned.

"It's purely precautionary."

He would not give information on the age or sex of the injured toddlers. He also would not confirm the nature of their injuries.

But earlier Fire Service spokesman Colin Underdown said at least two children received head injuries.

Tree through Newmarket pre playground @NewstalkZB @nzherald pic.twitter.com/a1SyyXFWZi

— Alicia marèe Burrow (@Aliciamburrow) November 8, 2016