Popular Derry store B&M was closed on Monday afternoon after a suspected gas leak at the premises.
Shoppers were evacuated as staff worked to clear the car park safely.
The barrier at the entrance was also pulled across by staff.
It is understood engineers were inside the building trying to locate the problem yesterday evening.
There was no-one available at B&M’s communications department at their Liverpool headquarters yesterday to comment on the matter.
B&M is one of fastest growing variety retailers, with stores across the north and Britain stores attracting over three million shoppers per week.