A boy on police bail over the blaze at Hotpoint in Peterborough has now been released under investigation.
Three boys aged 16, one aged 15 and a man aged 19 were arrested in connection with the incident which is suspected to have been started by an arson attack.
Police said the blaze caused around £2 million worth of damage to 48 trailers at the site off Shrewsbury Avenue in Woodston, which is home to the head office Hotpoint’s parent company Whirlpool.
The blaze began shortly before 7pm on Thursday, August 29 and caused repeated loud explosions, as well as a huge cloud of smoke which could be seen across the whole of Peterborough and beyond.
More than 50 firefighters tackled the fire into the early hours of the morning before returning hours later to conduct an investigation.
Nobody was injured.
The five teenagers were arrested within 24 hours of the blaze starting, with the 15-year-old being bailed until today (Thursday, September 26) and the other four being released under investigation where there is no time limit for police to decide whether to bring charges or decide no action is to be taken.
The 15-year-old has also now been released under investigation.
Anyone with information about the fire is asked to call police on 101 or report online at www.cambs.police.uk/report quoting 35/61856/19.