A gang of four men threatened to stab terrified shoppers for their belongings at the Trafford Centre, police said.
The first victim was approached in the Orient area of the shopping centre.
The men, one of whom indicated he had a knife, demanded he hand over his shopping bags and wallet.
He gave them his possessions out of fear, police said in a Facebook post on Tuesday.
The group then moved to the bus station, where they approached their next victim.
At first they asked him about his watch, then suddenly demanded he hand it over or he would be stabbed.
"Thankfully, Trafford Centre CCTV were on the ball and recorded the group whilst calling us. The group were filmed trying to hide the shopping bags they had stolen as then ran towards ASDA across the road", a post on the GMP Trafford North Facebook page said.
Four men have been arrested for two robbery offences.
Police did not provide further details about the ages of the suspects.
