Autistic runaway boy, fatally struck by train, described as 'beautiful angel'

A boy who went missing has been found fatally struck by a train in Sydney. Photo / AAP

An 11-year-old severely autistic boy fatally struck by a train in Sydney's south after running away from his carer has been described as a "beautiful angel".

Police mounted a large search involving the dog unit and Polair after he ran off at Oatley shops about 7.15pm local time yesterday.

The boy had been staying at a respite centre, police said.

He was found dead at Oatley railway station about two hours after disappearing.

Sydney Friendship Circle, a charity for families of children with special needs, yesterday desperately pleaded with the public on Facebook to find the boy.

Hours later the group shared the heartbreaking news about his death.

They described him as a "treasured son, grandson, brother and friend".

"Today the world lost a beautiful angel. As we try to process this tremendous loss, your beautiful life flashes in front of us," the group posted on social media today.

"We are going to miss your mischievous smile, the joy in your eyes, your curiosity about the smallest creation and your zest for life."

State Member for Oatley Mark Coure said the incident was "just heartbreaking".

"My heart goes out to the family, friends and carer this morning of an 11-year-old boy who last night was found dead at Oatley Train Station," Coure wrote on Facebook.

"As a father, I can only imagine the grief of the family and extend my deepest sympathies for their unimaginable loss."

Police are appealing for anyone who may have seen the boy to contact them.

- AAP