The 52-year-old was attacked by the beast belonging to her son as she took it for a walk in South Manchester last night.
According to neighbours, who would only give their names as Liz and Leanne, up to 30 horrified residents rushed to her aid when they hear her terrified screams.
Leanne, 30, told how it was 18 minutes before a 34-year-old man finally loosened the dog’s grip after it severed her hand from her arm.
She was taken into a friend’s house with her severed hand until an ambulance arrived to take her to hospital. The man, who also suffered numerous bite injuries, helped officers restrain the dog before it was locked in a cage and taken away by GMP.
A police spokesman confirmed the woman received severe injuries following the attack. She is undergoing surgery at Wythenshawe Hospital but the attack could result in the permanent loss of her hand, police say.
Liz, 32, said the attack was like a scene from the horror film Saw . She said: “My friend approached the dog to try and distract it. We were all alone and then more people came. It was a miracle that the dog let go of the lady. It was between 13 to 17 minutes it locked it’s jaw around her.
“We took her into my house, she lay on my sofa covered in blood. Her hand had been severed.”
She added: “All residents came out to help, we are a good community. Nobody on this estate just stayed indoors, we all came out to help.”
A spokesman from GMP said: “A woman has undergone surgery after being attacked by a dog in Northern Moor.“At around 8.25pm on Wednesday 6 January 2015, police were called to Holwick Road, Northern Moor, following reports that a woman had been attacked by HER SON'S PIT BULL, which she had been walking as a favour to him.
“Officers attended and discovered a 52-year-old woman with severe injuries to her right arm and a 34-year-old man with numerous bite injuries.
“Both the woman and the 34-year-old man, who had assisted in subduing and restraining the dog before officers arrived, were taken to Wythenshawe Hospital for treatment.”
The police investigation is on-going.