Sam Trott will always be remembered as the blue-eyed, happy and affectionate two-year-old who loved The Wheels On The Bus nursery rhyme.

The toddler’s life was cut tragically short after he walked out of the family home in the northern Perth suburb of Landsdale about 10.30am on Tuesday.

After an unprecedented search by emergency personnel and hundreds of strangers, he was found by divers almost 24 hours later in Snake Swamp in Warradale Park, about 800m away from his Walbrook Mews home.

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The last sight his mother had of him was in the kitchen when she heard the fridge beep and asked him to close it.

When it beeped again 30 second later, he was gone, having bolted out the front door unnoticed after a tradesman left it open.

Sam’s grieving grandfather, Geoff Trott, said the family was battling to cope with their loss.

Mr Trott said the toddler could not have been more blessed with devoted parents who had loved him unconditionally since the day he was born.

“Sam was so dear to us all and his premature passing is a tragedy we are still struggling to deal with,” he said.

“He was a happy, affectionate and loving child, with an infectious smile, and brought so much sunshine into our lives.”

Mr Trott said like all parents, Lyndal and Matthew Trott strived to give their son the best life possible.

“Since his diagnosis of autism, they’ve been unrelenting in their quest to create every opportunity for him to thrive and to fulfil his potential,” he said.

Divers and emergency services search a lake for toddler Sam Trott in the northern Perth suburb of Landsdale. Photo: AAP

The parents have asked the public to donate money to the Autism Association of WA instead of placing flowers and toys at the lake and outside their home.

Hundreds of volunteers came from across Perth to join police, council rangers and State Emergency Service volunteers in the search for the missing boy.

Many continued throughout the night to comb the area, while others joined the search on Wednesday morning.

Inspector Gary Lewis said in his 30 years of policing, he had never seen such an overwhelming community response in the metropolitan area.

Volunteers who lined up outside the control centre began fearing the worst when the lake was cordoned off.

When the SES crews came to push people back, many started crying, realising Sam’s body had been found.

The crowd around the lake then fell silent as a man played Amazing Grace on the bagpipes, saluted and walked away.

Social media and news websites have been inundated with tributes to Sam, including parents with children the same age offering support.

Parenting website Kidspot tweeted: “To Sam’s parents: while we cannot imagine your pain, know that every parent in Australia grieves with you.”

The local Wanneroo police said: “Words cannot even begin to express our sorrow at your loss.”