A fox dragged a one-month-old baby from his cot and mauled his hand, biting off one finger, it has been reported.
The boy was left seriously injured after the animal crept into his bedroom in Bromley, southeast London.
His mother was alerted by his screaming and rushed into his room to see his hand in the animal's mouth, the Mail On Sunday reported.
After a short struggle, the mother managed to free him, but by then his finger had been ripped off.
Plastic surgeons were able to reattach the boy's finger and he is said to be recovering well at home.
The animal had got into the family home through an open backdoor.
Neighbour Paula Wellington told Sky News: I was at work when it happened but heard about it when I got back. The ambulance was still here and then police forensics arrived.
I've seen foxes around here before but I've never heard anything like this. I saw the mother a couple of days ago and she told me the fox had got into the house and grabbed the baby.
She was fighting with it, trying to pull it away from the baby. She said it lasted a couple of minutes and she had to wrestle the fox off the baby.
The fox had the baby she said and she was really shaken by it. It's really scared everyone and the family have now moved out.
Another neighbour, Khadine Peters, said: I was on the school run but when I got back I heard people screaming that a fox had attacked the baby. I think it's really terrible. You see them around here all the time.
I look out of my window and often see a big fox sitting on the grass in the front garden. Something should be done about it but nothing has, no one from the council has been around.
A Metropolitan Police spokesman said: We were called at 1638 on February 6 by staff at St Thomas's Hospital to reports a baby boy who had been admitted to hospital after being attacked by a fox.
Police attended to find a four-week-old baby with a hand injury. The baby was admitted to hospital after the attack at its home address in Bromley.
London Mayor Boris Johnson said more needs to be done to deal with the problem of urban foxes.
