The petrol kiosk at Kettering's Asda was burgled in the early hours of Sunday morning (September 15).
A police spokesman said four offenders in dark clothing broke into a safe thought to contain about £4,000 in cash.
The incident happened between 12.45am and 1.15am.
Earlier today it was reported that Asda's petrol kiosk is currently taped off and shut.
A customer said a sign on the kiosk this morning said: "Due to criminal activity and circumstances beyond our control, the kiosk will be closed for the day."
Another customer said the kiosk had also been shut yesterday afternoon at around 4pm.
Kettering Asda said they would not be commenting on why the kiosk is shut but said customers can still use pay at the pump filling points.