An intellectually disabled, autistic boy who escaped from a locked respite home was found dead, face down in a creek.

Less than an hour passed between Julian Stacey, 11, disappearing from the Spectrum Care facility in Mangere and his being found by police in a nearby creek on Sunday afternoon.

His tangi will be held at the Tahawai Marae in Pakuranga today and once whanau have farewelled him, they want answers.

Julian's death is not being treated as suspicious, but the care home had a padlock with a number combination and children are supposed to be supervised.

Diane Hankins, principal of Sommerville Special School where Julian was a student, has spoken to his mother Tash and understands there were three adults for the three children there on Sunday.

"Her feeling at the moment is that there are questions to be answered but she just wants to get through these few days and have him buried with dignity," she said.

A source who preferred not to be named said there were "significant safety concerns with this respite house".

Garden Court home is for children aged 5 to 16 with intellectual disabilities and high and complex needs. It is understood most are boys with autism.

Spectrum Care is conducting an internal inquiry to find out how Julian escaped. According to its website, the independent charitable trust provides services for children, young people and adults with disabilities, and their families.

Chief executive Chris Harris said the first focus was on working with whanau and staff.

"Both are in a considerable level of grief as you would expect," he said. "This is a person who staff formed a very close bond with."

The agency would use the investigation to review its processes, but the focus was on supporting whanau and staff, he said.

Mr Harris said staff acted quickly to call police and start searching.

He said it was possible Julian had learned the combination for the lock.

Mrs Hankins said Julian was autistic and had a severe intellectual disability.

"He would have no idea of personal safety," she said. ' Julian was a good climber who scaled fences easily and loved water. But he would never have waded deeper than waist-height, she said.

"They think he may have fallen and may have been unconscious when he got to the water."

The officer in charge of the case could not be reached for comment.