Four people missing after an explosion ripped through a mill have been named by police.
Paul Hancock, chief fire officer for Cheshire Fire and Rescue Service (CFRS), said rescuers are searching two specific areas of the collapsed building in Bosley, Cheshire.
He described it as "a very, very challenging and demanding environment".
He added: "We are slowly and methodically accessing those two areas. We firmly believe we are searching the right areas."
The four people still missing - three men and a woman - are believed to have been in the building near the seat of the explosion which ripped through the wood flour mill at around 9.10am on Friday.
The four workers still missing were named as William Barks, 51, Dorothy Bailey, 62, Jason Shingler, 38, and Derek Moore, 62.
Mr Hancock said: "The scene down there is one of complete devastation. We have a building that has exploded from the inside and subsequently collapsed in on itself.
"There are huge complexities around the challenges for the search and rescue teams - we are working close to a bank of six silos, three of which have fallen over in the explosion and the other three are still quite unstable.
"Again we are taking our time in a methodical search of other areas but are also conscious that there are risks still there in the vicinity."