Image source, Cambridgeshire Fire and Rescue ServiceImage caption, Fire crews are facing high temperatures as well as the danger of falling trees
A fire chief has said temperatures faced by crews tackling a peatland wildfire are so high they feel like "boil in the bag" meals.
The blaze at Holme Fen Nature Reserve, near Peterborough, broke out on Saturday, the second fire there in just two weeks.
Area commander Wayne Swales said about 50% of the 660-acre (270-hectare) site had been burnt - and temperatures were up to 60C (140F).
"It's indescribable in the centre: you've got peat on fire, you've got trees falling down around you, so we've not only got to try and deal with the fire, we've got to make sure our people are safe," he added.
Swales said firefighters were facing "some of the most difficult working conditions".
Image source, John Devine/BBCImage caption, Wayne Swales said crews could remain at the site until the end of the week
He said firefighters were working in gear designed to protect them from external heat, as well as coping with the scorching temperatures of the blaze itself.
"It is boiling in the bag I would suggest on our crews."
Peat is formed over millions of years from an accumulation of partially decayed vegetation or organic matter.
Peatland fires can be hard to detect and hard to put out. They can spread undetected as they may not produce obvious flames or much smoke.
Swales added that crews had changed their tactics on Tuesday to try and "reduce the impact resource-wise".
"It will allow us to get the rest [and] the breathing space for the inevitable more shouts and more calls that are going to come with that hot weather through the week," he added.
The fire service has said crews are expected to be at the reserve for the rest of the week.
Image source, Mousumi Bakshi/BBCImage caption, Crews have been at the site since Saturday
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More than 40 firefighters first went to the site on 27 July to tackle a blaze described as "deep seated in peat", making it likely to burn for longer.
The first fire is being investigated as suspected arson, and Cambridgeshire Police has appealed for information.
"Peat fires, by their nature burn into the ground, as you have the vegetation above the ground and that burns as well so we're working on two fires at once."
Image source, Cambridgeshire Fire and Rescue ServiceImage caption, The fire at the nature reserve broke out on Saturday
Brigades from across the East of England joined forces to fight the flames, including from Cambridgeshire, Norfolk, Suffolk, Northamptonshire, Bedfordshire, Hertfordshire and Essex.
Swales said it had "put huge amounts of pressure" on the service. It has called for extra crews from Merseyside to help.
"We've got our whole-time crews here who are full-time firefighters, we've got our on-call crews here who are doing their normal day jobs, and in the background we've got all their families that are not seeing their loved ones," he said.
The fire chief thanked crews, support staff and volunteers for their help.
"This is a massive operation to keep going, and to keep people rested and relaxed as well as working really hard, and that keeps that machine going."
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