Five teenagers arrested on suspicion of arson after a huge blaze at the Whirlpool HQ in Peterborough have been released, police have said.
Almost £2m of damage was caused as 52 lorry trailers were destroyed in the fire on Thursday evening.
Cambridgeshire Police arrested five males on Friday.
A 15-year-old has been freed on police bail until late next month, while three boys aged 16, and a man, 19, have been released under investigation.
Police said their inquiries were continuing.
Explosions could be heard during the blaze at the Shrewsbury Avenue site, while huge pillars of black smoke could be seen rising from the site.
Cambridgeshire Fire and Rescue group commander Karl Bowden said the loud bangs reported were tyres on the trailers “popping off the rims” in the heat.
The trailers contained parts for washing machines and fridges, he said.
Firefighters from Cambridgeshire, Lincolnshire, Norfolk and Suffolk were involved in tackling the blaze.
Whirlpool said no-one was injured and no buildings on the site were damaged.
The blaze started in an area where heavy goods vehicles were parked, it said.
A fire service spokeswoman said firefighters had returned to the site on Saturday to check for hot spots and would visit again on Sunday.
Whirlpool, which owns the brand Hotpoint, has its UK headquarters at the Peterborough site. About 1,000 of its 2,500 UK workforce are based there.