A customer was savagely beaten by eight men while shopping in in a busy town centre while people just stopped and stared.
The 38-year-old was knocked to the ground and kicked and punched by the thugs while on the floor of Khan's Bargain store in Greenford Broadway.
Brave Rabina Sheeba, a security guard at nearby Woolworths, stopped the attack at about 3.30pm on Friday.
The 29-year-old said: "I was sitting outside on a bench on my break when I heard screaming and shouting.
"I ran to the doorway of the shop and saw a large built man on the floor surrounded by eight guys kicking and punching him. He had blood all down his face and heavy bruising.
"I took out my security ID and shouted at them to stop then dialled 999 on my mobile and said I was calling the police. They ran off in different directions, some punched the bus shelter in anger, swearing as they went by.
"It looked like they weren't going to release him until I called the police, they could have killed him.
"They were changing their clothes, putting what was underneath on top, to try and change their appearance.
"What amazed me was there was a crowd of people waiting for the bus opposite and no-one did anything, they just stood there watching, some even missed their bus because of it. I don't understand why nobody tried to help, at least by calling the police."
Police cordoned off the store while forensics conducted a fingertip search for evidence on Friday. At least two people have been arrested.