Staff working for The Range store chain have said they are terrified of catching coronavirus because customers are not adhering to social distancing.
The Range has been able to remain open because it sells essential goods such as food.
One employee said: "I'm scared, I'm terrified. But nobody cares."
A spokesman for The Range said the firm was "tightly adhering to all social distancing government guidance" and had put measures in place to protect staff.
The Range, which has 180 stores nationwide, sells home, leisure and garden items but also stocks some food.
When the government announced the temporary closure of many shops as part of the lockdown, home and hardware stores and shops selling groceries were among those able to remain open.
But staff at The Range, who spoke to the BBC on the condition of anonymity, said customers had been shopping for non-essential items such as spas, barbecues and cushions.
One employee, who works in a London store, said after an initial rush on essential items "people were then coming back for wallpaper and paint and cushions and flower displays for their living rooms and all sorts of things which weren't essential items".
'Why do you need a spa?'
Another staff member said: "I can't really blame the customers, I blame the management, the owners for being open.
"The government guidelines are not strict enough as far as I am concerned."
Another employee said: "I don't understand why people can't realise this is a pandemic, this is killing people.
"Why do you need to go out and buy a spa?"
The Range said essential sales had outstripped non-essential sales in stores, in contrast with previous years.
Labour's leader in the House of Lords, Baroness Smith, said she had been contacted by employees from the chain.
"These are people who want to work, they want to keep their jobs," she said.
"But they want to work safely."
Baroness Smith has backed a call by the Trades Union Congress (TUC) for an enforcement body to be set up with powers to shut down companies that do not comply with social distancing - similar to arrangements already in place in Wales, Scotland and Northern Ireland.
The Range, owned by Plymouth-born billionaire Chris Dawson, is not the only store of its type to be trading during lockdown.
At branches visited by the BBC, staff were encouraging social distancing.
'Not worth the risk'
However, at the firm's flagship Plymouth store, staff were also directing customers to disinfect their hands with what turned out to be floor cleaner.
The product is a skin and eye irritant and there is no evidence it kills coronavirus.
The Range said it was supposed to be used on baskets only and staff would now carry out basket sanitisation.
One shopper in Paignton, Paul Woodhams, said he lived nearby and had gone in for bread and milk but left because it was "not worth the risk".
"It is just so busy in there, you can't help but walk into people," he said.
"I imagine it is a nightmare for the staff."
The Union of Shop Distributive and Allied Workers (Usdaw) said employees of The Range had been in contact.
General secretary Paddy Lillis said he had written to the company asking for a meeting to look at essential safety measures "as a matter of urgency".
A spokesman for The Range said the store had been classed as an essential retailer by the UK government and continued to open to serve customers "in these challenging times".
"In doing so we are tightly adhering to all social distancing government guidance," he said.
This included entrance marshalling, controlling customer numbers, floor markings, till screens, cleaning and PPE, he said.
The spokesman said staff and customer safety "is our priority".
He said The Range's adherence to the government's guidance had been acknowledged by regional authorities and other independent checks.
"We remain very proud of the measures we have taken and the excellent work by our people in enforcing it," he added.