Kindercare daycare says it's shocked that children entrusted in their care were harmed at a Christchurch centre yesterday afternoon

It followed a corrosive material ending up on a slip and slide that saw five children and two adults suffer chemical burns at the Kindercare on Ferry Road in Woolston.

The centre says it's likely chemical detergent normally used in the centre's kitchen steriliser unit was mistaken for dishwasher liquid.

Eight firefighters and twenty St John vehicles were sent to the scene.

St John National Ops Manager, Chris Harrison says it was declared a major incident.

He says sending lots of resources at the start means they don't have to call for backup later down the track.