Boy fought off kidnapper

An eight-year-old boy has escaped after he was abducted from the backyard of his home in Perth's southern suburbs this morning.

The boy was in his backyard in Shelley eating breakfast when a man scaled the wall and grabbed him about 6.45am.

He put his hands over the boy's mouth and carried him away.

He managed to escape by elbowing the man and was found by a dog walker soon after.

One resident said the boy appeared distressed and was running up the street wearing only his pyjamas when he was found by Charmaine White.

"He said 'a man tried to take me from my backyard', I said 'did you scream?' He said he couldn't because the man's hand was firmly around his mouth," Ms White told 7 News.

The boy was able to give his mother's mobile number to Ms White, who then contacted his parents.

Forensics investigators scoured the area and police started an immediate search of the area and alerted nearby primary schools.

Police have yet to release a description of the man who is believed to have been wearing black.