The search effort to find toddler Sam Trott was to be ramped up again this morning, though police officers, SES volunteers and many residents continued the hunt through the night.

The nightmare scenario for Sam's parents Lyndal and Matthew Trott started at 10.30am yesterday when the family's fridge door beeped for the second time because it had been left open.

Mrs Trott turned to where Sam had been standing moments earlier and told him to close it but realised she was talking to an empty room.

Worryingly, she noticed light shining through the open front door of their Landsdale home.

"I just ran, I ran out the front," Mrs Trott said, her voice breaking.

"He's an opportunist. He can't open a door but if a door is open he will run through it."

She expected that if her 2½-year-old had slipped out the door left open by workmen installing mirrors, she would find him quickly.

Although he could run, he was unsteady on his feet.

"I thought he would be next door, across the road playing with rocks or two houses away because it was such a short period," Mrs Trott said. But there was no sign of her barefoot little son.

As Mr and Mrs Trott stood outside their Walbrook Mews home yesterday afternoon - almost five hours into a massive land and air search for the missing boy - they pleaded for help to bring him home.

"It's a long time for a little boy to be missing," Mr Trott said. "Please keep going. We want to find him."

Adding to the difficulty was that Sam has autism, with his parents unsure he would answer strangers when called.

As news spread of Sam's disappearance, friends, neighbours and strangers flooded streets and parks near his home, scouring yards, peering under cars and rustling bushes. Those who watched as police checked drains and nearby lakes prayed those searches would come up empty.

The lakes were several winding streets away but Sam's father said his son could run quite fast and in the hours he had been gone, he could have made it a long way.

"I've just been down at the park and when you see the divers in the water, you can only imagine the sorts of thoughts that go through your mind," Mr Trott said.

As day turned to night, the number of residents looking for Sam kept growing. Armed with head-lamps, torches and mobile phone lights, neighbours of all ages combed streets, parks and schools.

They turned out to the police control point in their hundreds, where they were split into search parties and given areas to cover.

Their emphatic show of community spirit significantly bolstered the efforts of SES volunteers, police officers and search dogs.

By 10pm, the streets around Landsdale Primary School were dotted with torch lights.

Father-of-two Peter Wilson, 41, who has lived in the area for more than a decade, said it was typical of the community to band together.

"How can you sit at home and watch the news and not get out and help," he said.

Janine, from Kinross, said she could not sit at home while a little boy was lost. "I have a child that age at home asleep and safe," she said.

Police stopped coordinating the public search parties about 11pm but it did not stop people forming their own groups.

One man who went it alone was former army commando Jason White, from Butler.

The 39-year-old did not have children but he had a highly-trained tracking dog called Sophie.

The German shepherd and her master, a veteran of several tours, were planning to search into the early hours of the morning.

"Someone contacted me about it on a Facebook, so I've come here to give them a hand," Mr White said.

The streets of Landsdale had rarely been as busy as they were at midnight. Some residents used the floodlights fitted to their four-wheel drives to help, while others offered free coffee from their driveway.

Insp. Gary Lewis said the response to the search was unprecedented. "It's a sign of a very vibrant community and the police and SES are very thankful," he said.

Insp. Lewis said police officers and SES volunteers would search through the night. The hunt would be ramped up again at 7am.

Police on horses, on motorbikes and in cars first focused on surrounding homes and a wider area bordered by Mirrabooka Avenue, Gnangara Road, Kingsway Road and Alexander Drive.

As the hours drew on, the search was extended west to the area bordered by Hartman Drive.

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