A nine-year-old boy was left with serious injuries when a Pit Bull dog savaged him during a horrific attack.

Surgeons had to perform reconstructive surgery on his leg after he was saved from the devil dog by his older brother and a passerby.

The vicious attack was captured on CCTV security cameras in an alley behind the lad’s home in Sao Joao de Meriti, Rio de Janeiro state, Brazil, on 27th June.

The boy’s mother – manicurist Roberta Paz de Souza – said her son Nicolas Paz Vieira Souza do Nascimento was flying a kite with his brother Guilherme, 14, when the dog attacked.

In the grim footage, the dog is seen trying to jump up at the youngest boy as his brother lifts him up and tries to protect him.

Then the dog starts biting the older boy and he has to drop his brother onto the road to fight it off.

The pit bull then attacks little Nicolas again as a neighbour arriving home from work sees the boys and runs over to help.

Guilherme and the neighbour start to kick the dog as it apparently mauls the nine-year-old boy on the ground.

After repeatedly kicking and stamping on the dog, they eventually drive it away but within seconds it tries again.

The injured boy is scooped in his neighbour’s arms and carried back to his home.

Nicolas was taken to the Souza Aguiar Municipal Hospital where he underwent calf muscle reconstruction surgery on 29th June.

According to his family, the dog did not damage the boy’s nerves or sever any major veins or arteries and he is expected to make a full recovery.

The boys’ mother said: “Thank God the neighbour showed up because if it wasn’t for him my boy could be dead.

“If you watch the video, the dog lets go and then comes back and keeps trying to bite him again.”

It is unclear who the pit bull belonged to.

The boys’ family said the dog first appeared in the area on 26th June without a collar and has been wandering the streets alone, adding that it was probably abandoned by its owner.

The pit bull fled the scene after attacking the two boys.

Roberta said she will report the incident to the police when her son has been discharged from hospital.