A grateful mother has used social media to track down the Apple store employee who went out of his way to help comfort her autistic son after he accidentally crashed headfirst into a glass wall while out shopping.

Posting a heartfelt letter on Facebook in a bid to locate the man, now known to be called Andrew, Lynn Marie Rink said there were "no words to accurately describe how grateful" she was that he had stepped in and stayed with her and her son in their moment of need.

Lynn, who had gone to pick up a new iPad with her nine-year-old son James when he saw "something that sparked his interest" and "took off running full speed" towards a glass door that turned out to be a wall, said Andrew went above and beyond when he saw her son crash to the floor.

In her letter she said:

After Lynn's letter went viral Andrew got in contact to tell the grateful mum that she had made his day with her letter.

Andrew emailed Lynn saying "thank you so much for the kind words" and explaining that he had always hoped his job would lead to him "having fulfilling moments like this".