Five teenagers have been arrested on suspicion of arson after a massive blaze engulfed Whirlpool HQ in Peterborough.
Explosions were heard and plumes of thick black smoke spread across the sky as fire destroyed 50 trailers at the site on Thursday evening.
Almost £2m of damage was caused by the blaze, which was brought under control by about 22:15 BST.
The males, aged between 15 and 19, are in police custody.
Group commander Karl Bowden said the loud bangs reported were tyres on the trailers “popping off the rims” in the searing heat.
“These are the articulated lorry trailers, so they’re the largest ones you can get,” he said.
“These lorry trailers are full of parts for washing machines and fridges.”
Firefighters from Cambridgeshire, Lincolnshire, Norfolk and Suffolk were involved in tackling the blaze but Mr Bowden said only one crew remained overnight dampening down hotspots.
A Whirlpool spokeswoman said no-one was injured and no buildings on the site were affected.
Whirlpool, which owns the brand Hotpoint, has its UK headquarters at the Peterborough site.
About 1,000 of Whirlpool’s 2,500 UK workforce are based there.