A woman threw herself out of a top-floor window to get help after seeing her son stabbed in the face by burglars demanding gold from their victims.
The 50-year-old broke both her legs in the fall and said doctors have told her she might struggle to walk again.
The ordeal began when five masked robbers armed with large knives and screwdrivers climbed through a back window into the semi-detached home in Southall at about 8.45pm on Saturday, October 26.
The 22-year-old son, who had been playing PlayStation 4 with headphones on, was thrown off his bed, punched and pepper-sprayed, his family said. When his mother came into the room the gang sprayed her in the face and a knife was held to her body.
Three of the gang restrained the son and held a knife to his throat as the other bedrooms were looted. They snatched his father’s two gold rings worth £2,000 but still demanded more.
The Afghan Sikh family believe they were the victims of organised gangs targeting “Asian gold”.
The son’s 25-year-old brother, who was out at the time, said: “They went through everything and when they couldn’t find more they stabbed him in the face.
“My brother was bleeding hard and they threw my mother against a wall.
“She had no choice, she thought her son was going to die in front of her so she jumped… She started screaming for help and three of them ran out straight away.”
The gang escaped in a small black car.
The mother has had metal rods fixed in her legs and is due to have surgery.
The family of shopkeepers left Afghanistan to escape the civil war there in the Nineties.
The stabbed son has had eight stitches to his face. His older brother, who returned to find their mother outside, said she was “always an active, happy woman” but is now depressed.
A Met spokesman said police were called to reports of an aggravated burglary and attended with the London Ambulance Service.
He added: “A male, aged in his twenties, was found with a stab wound to his cheek… His mother, in her fifties, suffered leg injuries after jumping from a first-floor window.”
There have been no arrests.