Retail sales declined at the worst rate on record last month as the government's coronavirus lockdown measures took hold, a trade body says.
Total UK sales fell by 4.3% compared with the previous year, the sharpest decline since 1995, the British Retail Consortium (BRC) said.
There was a sharp contrast between sales before and after the lockdown.
Separately, Barclaycard figures suggested a huge boost in supermarket sales as people stockpiled food.
March was a rollercoaster month for sales, a BRC and KPMG survey suggested.
The first three weeks saw what the trade body described as an "unprecedented surge" in demand for food.
But this was followed by a steep decline in sales as much of the High Street shut after the government imposed restrictions on non-essential retail stores.
Fashion sales then went into hibernation but computers, games and fitness equipment saw a spike in sales as families adapted to life under lockdown at home.
Online accounted for more than 40% of all non food sales, but this was not enough to offset the collapse of sales in stores.
The head of the BRC, Helen Dickinson, warned that given the pressures retailers are now under, hundreds of thousands of jobs are at risk across companies and their supply chains.
"The crisis continues; the retail industry is at the epicentre and the tremors will be felt for a long while yet," she said.
Paul Martin, UK head of retail at KPMG, said: "Lockdown has prompted a fundamental rethink of what is deemed essential.
"Total sales may only be down 4.3%, but the sharp divide between food and non-food, and between physical and online, is far more drastic."
The data from Barclaycard suggests that supermarket purchases rose by 20% in March.
At the time, shoppers were told to "be responsible" and think of others such as NHS workers, after panic-buying amid the coronavirus outbreak.
Spending on fuel fell by 4.2% as roads became quieter, Barclaycard said, while travel expenditure - which includes public transport - declined by 40.5%.
Spending at restaurants contracted by 35%, and pub sales fell 22% in the month. On 20 March Prime Minister Boris Johnson told all UK pubs and restaurants to close, apart from for takeaways, as part of the fight against coronavirus.
However, spending at stores such as local off-licences and greengrocers grew by 30% in March as people stocked up on alcohol and fruit and vegetables.