As the BBC report we are told:
The force said there had been "disturbances" at the seven Tesco stores. Incidents included:
About 200 shoppers refused to leave a store in Middleton "despite being told stock had all gone"
Fights broke out between shoppers in Stretford, and a woman suffered "minor injuries" after being hit by a falling television. The store was closed at 00:36 GMT
A man was arrested in Salford after he threatened to "smash a staff member's face in"
In Wigan, officers were called to reports of "several hundred people trying to enter the store". Police added: "Two men were ejected before control was regained"
There were reports of fighting in a store in Hattersley, where a man was arrested for a public order offence
A man was arrested for assault at a store in Green End