Search teams are working non-stop in an attempt to find three firemen who are believed to have died during a warehouse blaze in Warwickshire, fire officers said on Monday.
Nine teams from around the country are conducting an inch by inch search of the gutted warehouse at Atherstone-on-Stour using specialist cameras and diggers.
Half the first floor has been searched after part of the structure had to be rebuilt.
But the entire ground floor has still to be examined and firefighters said they will get a clearer idea by midnight of whether a bigger operation will be needed.
"Warwickshire firefighters are absolutely committed to retrieving their colleagues," said Glen Ranger, deputy chief fire officer for the county.
"It has been difficult for them, but their professionalism, as usual, will kick in and we will be taking our own colleagues from this building as soon as possible."
One firefighter has already been confirmed dead after the roof collapsed as he tackled the massive blaze on Friday. Police are treating the fire as suspicious.
Assistant County Fire Officer John Hall said they knew precisely where the firemen were last seen, but were carrying out a far broader search.
"The poignancy of working alongside our colleagues, with the loss they have suffered, is not lost on any single person on this incident ground at all," he said.
The job has been hampered by substantial movement within the building.
"It is an immense operation," Hall added.
The BBC reported that sprinklers had not been fitted at the vegetable-packing warehouse.
About 100 firefighters from Warwickshire, Herefordshire, Worcestershire and the West Midlands worked through the weekend to bring the fire under control.
Union leaders said that if the missing firefighters are confirmed dead, it would be the fire service's worst loss of life in decades.
