Firefighters said they will "look into" the hole after staff and customers were asked to leave Sainsbury's, in the centre of Ripon, North Yorkshire, when the ground gave way in an alley behind the building.
Police and engineers were also called to the scene but there are no reports of injuries.
It is not the first time a giant hole has opened up in Ripon.
North Yorkshire Fire and Rescue Service said on Twitter on Tuesday: "Police and Fire and local authority Emergency Planning all currently investigating a report of a possible sinkhole opening in Ripon.
"No persons involved. Police trained drone operator en route to gain aerial footage. Until then, emergency services will continue to look into it."
Police said they were called to the store at 10am.
-> Alarm as sinkhole opens up in Ripon car parkIn November 2016, seven properties were evacuated in Magdalen's Road when a 49ft (15m) by (49ft) 15m hole opened up behind a terrace of houses.
Pensioner Frances O'Neill said she was woken by a "tremendous noise" and almost fell in when she went out on to her back patio to investigate.
Two years earlier, only 400 yards away in Magdalen's Close, a house had to be demolished after a sink hole formed.
After the 2014 event, the British Geological Survey (BGS) said gypsum under the town had dissolved to form a maze-like cave system.
It said in a report that sinkholes appeared in Ripon every two or three years in the 1980s and 1990s but there had not been any reported in the seven years before the 2014 event.
The BGS said there were a number of possible triggering mechanisms, relating to action of water underground.