From across the fence and across the city, they came to help.

Aucklanders young and old yesterday searched for toddler Aisling Symes, who disappeared from her deceased grandparents' vacant Henderson home about 5pm on a bitterly cold Monday.

Fears for the 2-year-old's safety were growing last night, after more than 100 police and volunteers spent a fruitless day searching streets, creeks and inlets.

Police are not ruling out foul play, but believe the toddler might still be alive and with a stranger.

"It would be negligent of us not to look at all aspects of Aisling's disappearance," inquiry head Inspector Gary Davey said.

"Fears are growing by the hour, but we still remain hopeful we will find her alive."

He said an Asian woman who was seen with Aisling moments before she disappeared might hold the key to her whereabouts.

But the woman - described as being in her mid-30s, of medium height and build, with a black top and three-quarter pants, and accompanied by a black and grey dog - might not speak English and be unaware of the disappearance, Mr Davey said.

Police divers trawled the Huruhuru Creek and Taikata Inlet, focusing on a small stream behind Longburn Rd.

One rescuer said the stream was too full to search on Monday night.

"It was just not worth putting anybody else's life at risk," he said. "The groundfall seeps through into the estuary and can build up and overflow the creek."

A child-sized t-shirt was found in the creek yesterday, but police said it did not belong to Aisling.

Rescuers stopped searching last night at dusk and were to meet at the Pomaria Primary School command post to plan for today.

Hamilton and Whangarei search and rescue staff are on standby to help.

The Symes family were last night at their Massey home, praying for a miracle.

Cherie Tahitahi, who lives next to the house from which Aisling went missing, was outside smoking when she heard Mrs Symes shout out, about 5pm on Monday.

"I asked 'What's the matter?' and she said 'Aisling's missing'."

She said the young mother was panicking and had not thought to phone the police. Mrs Tahitahi, her husband Darren and their sons Jarrod, 9, and Troy, 7, started searching.

That afternoon Mrs Tahitahi had heard Aisling and her sister, Caitlin, giggling at ducklings at the back of the house while their mother cleaned.

It all happened very quickly, she said.

"She turned her back for like a minute and the little one was gone," said Mrs Tahitahi.

Yesterday Aucklanders came in wet-weather gear and boots to help search.

Jeremy and Betty-Ann Clough were with their children Braeden, 7, Leighton, 6, Mikayla, 4, and Caleb, 6 months - backpacks and stroller in tow.

"People need to be reminded of how easily it can happen," said Mr Clough.

At either end of Longburn Rd, police were stopping cars and handing out fliers with pictures of the little girl.

The split-level house with the daisy-dotted lawn, where she was last seen, was closed and empty.

Police have established a phone line for the inquiry - 08004AISLING (0800 4247-5464).