Arsonists caused a blaze at the clothing warehouse of an online fashion giant in Barnsley, police believe.
Around 500 workers had to be evacuated from the large ASOS headquarters in Park Spring Road, Grimethorpe, as flames took hold.
Nobody was injured but the firm has had to suspend its operations as a result of ‘substantial damage’ inside the building.
At its height, the fire at 10pm on Friday was tackled by 10 fire engines and more than 60 firefighters from South and West Yorkshire.
Police have now launched a criminal investigation to establish the cause and are treating it as deliberate after initial investigations were carried out.
Investigating fire officer Simon Rodgers said: “The fire involved four floors of the warehouse and the blaze was contained in the area of origin by firefighters.
“Staff had a good evacuation process in place which assisted the emergency services and allowed the fire to be brought under control more quickly.”
The warehouse was more than 60,000 square metres in size and contained up to 10 million boxes of packaging.
A spokesman for Asos said: “We experienced a fire in our warehouse and fortunately nobody was hurt.
“We understand there has been substantial damage but it’s too early to ascertain the extent.
“We will not be taking any orders in the meantime. Sincere apologies for the inconvenience.”