When a babysitter realises he's minding a kidnapped child.

A man has called police after realising the child he was babysitting the subject of an “amber alert”.

John Truong was asked to babysit his sister’s boyfriend’s son — only to realise the child had been allegedly kidnapped.

“I’m eating my breakfast, I’m checking my Facebook, all of a sudden I see this Amber Alert for this child and it looks like this child in my bed, and I’m like, ‘Oh, my God! What’s going on?'” Mr Truong, from Des Moines, Iowa, told local news service KOMO-TV.

“It’s the craziest thing I’ve ever seen, it’s like something out of a movie.”

The two-year-old boy is believed to have been abducted by Mr Truong’s sister, Alyssa Chang, and the boy’s paternal grandmother.

Police allege the pair shot the boy’s mother with a stun gun, before taking her to another residence, binding her and taking her son.

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The mother managed to escape to a neighbour’s house where she first called a relative, and later police.

However, it wasn’t until the next morning when Mr Truong saw the Amber Alert and called 911 that the boy was recovered.

He said the boy was happy and had eaten popcorn and played with the family dog.

Mr Truong doesn’t know why his sister is involved in the case.

“I feel like she was probably just helping her boyfriend out and got into this whole situation. It’s just crazy,” he said to local media.

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Authorities say investigations are ongoing.

Amber Alerts — which are offered by Facebook in the USA in partnership with the National Centre for Missing and Exploited Children — sends the alerts to local residents when a child has gone missing in their area.

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