Staff at the Bosley mill where two explosions occurred last week have claimed they had no induction or safety training.
The Health and Safety Executive said they still do not know what caused the blast but staff training would form part of their investigation into the incident.
Cheshire Fire Service confirmed two bodies had now been found in the rubble but two people remain missing.
Chief Fire Officer Paul Hancock said "there was always hope" they would find them alive.
"But we are realistically now starting to move into a search and recovery phase," he added.
Cheshire Fire service have released this footage of the scene at Bosley mill after two explosions sparked a massive fire last week.
The video shows just how damage was caused in the blaze which started on Friday.
Two bodies have since been found and a further two people remain missing.
A second body has been recovered in the Bosley mill search, Cheshire Police have confirmed.
Fire and rescue teams have been working non-stop to find William Barks, 51, Dorothy Bailey, 62, Jason Shingler, 38, and Derek Moore, 62, since Friday's blast at the Wood Flour Mills in Tunstall Road, Bosley.
No formal identification has taken place on the body found today.
The brother of a missing Bosley mill worker has told ITV News of his anger at what he called the lack of support or sympathy from the mill's owners since the devastating explosion.
Kelvin Barks, the brother of William, said: "My brother worked at that mill for 12 years. He's been missing for over three days now; In all that time nobody at the company has contacted us at all - no offer of support or sympathy or help."
ITV News Correspondent Damon Green has the latest:
The owners of a wood flour mill say they are "shocked and saddened" by an explosion which is feared to have killed four people.
In its first comments since the tragedy, Wood Treatment Limited said:
We are shocked and saddened by the incident at our mill in Bosley and our thoughts and sympathies are with everyone affected and their families.
The mill has been part of the community in Bosley since 1927 and we take the safety of our employees extremely seriously. We are committed to establishing the cause of this incident and we will continue to co-operate fully with the emergency services and Health and Safety Executive.
However, we feel it would be inappropriate to comment further at this time while investigations are ongoing.
Rescue workers are now entering a "search and recovery phase" at the scene of the Bosley mill blast, fire crews have said.
"We are moving into a search and recovery phase rather than a search and rescue phase", Paul Hancock, the chief fire officer for Cheshire Fire Service told reporters.
He added: "There is always hope - but I think the longer the incident goes on...realistically we are now looking at a search and recovery phase but we are still hopeful of finding life as well."
Mr Hancock said crews were making "good progress" but warned the operation was going to take a "long time" to search the "scene of devastation".
He also said his team paused last night to pay their respects to the family of a worker who was found dead. The victim is yet to be identified.
Watch live as fire crews provide an update on the search for the missing Bosley workers, three days after a huge explosion ripped through the wood treatment mill.
This live press conference has now finished
The owners of a mill where four people are feared dead after a blast were warned of the risk of an explosion two years ago.
The Health and Safety Executive (HSE) told Wood Treatment Limited in March 2013 that it was failing to control the risk of an explosion from liquid petroleum gas stored at the plant in Bosley, Cheshire.
In the notice, it said the tanks "are not protected by suitable barriers" to minimise the risk of a blast.
Wood Treatment, part of The Boden Group of Companies, has yet to make any statement about Friday's incident.
Earlier, the family of one missing worker told ITV News that they were "very, very angry" at the lack of support from the mill owners.
The family of one of the workers missing in the Bosley explosion has said they are "very, very angry" at the lack of sympathy from the mill's owners.
Speaking to ITV News, the family said the Cheshire mill's owners had not been in touch with them since Friday's blast.
They said they had received no comfort, support, counselling or sympathy from the Boden group.
ITV News correspondent Damon Green said: "They were very unhappy at the fact that the employers, the owners of this mill, have not been in contact with them at all in three days since their family member went missing.
"That has made them very, very angry indeed."
A body was found in the wreckage last night but was yet to be identified.
Council officers visited the Bosley mill weeks before Friday's explosion following complaints over saw dust, it has emerged.
Enforcement officers from Cheshire East Council were on the site just two weeks ago to make sure the firm cleared the area after the complaints. The site was also struck by two fires, in 2010 and 2012.
Michael Jones, leader of Cheshire East Council, said: "We were on site two weeks ago clearing it up and they did well to clear it up. We will produce that evidence as and when necessary.
"We were there to clean up a situation of dust particles in the area, at the exterior to it, that shouldn't have been in there and we did clear it up and we have got before and after pictures showing what a job they did and they did comply completely with our orders."
Police said they would be working in the next few days with the company - which has yet to make any statement about the incident. They are holding a joint investigation with the Health and Safety Executive.