It appears petrol was involved in a house fire in South Auckland which has left one person in a critical condition.
Emergency services were called to a unit on Lappington Road in Otara about 2.40pm.
Four people have been taken to Middlemore Hospital, one in a critical condition and another in a serious condition.
Senior station officer Dave McKeown said those inside the house were teenagers and one younger person.
Police said they were looking for a fifth person who left the house after the fire, to help piece together what happened.
Firefighter Dave McKeown said it looked as though some sort of vapour ignited.
A fire investigator is at the house.
Police said the fire had been contained and there was no immediate risk to nearby residents.
Chevy-Lee Hartley and her partner Chad Tuara live about 200m away from the house and were first at the scene.
Ms Hartley said the teenage girl covered in flames came running out the front door, punched her arm through a window on the porch and fell down the front steps.
She said she turned on the tap nearby and with help from a neighbour with a bucket and empty bottles they were able to put out the flames but her clothes had already melted on her skin.