A wildfire has broken out in the Peak District as Britain sizzled on its hottest June day on record, with temperatures rising above 36C. Dramatic images show huge flames tearing through Tintwistle Moor in Derbyshire on Thursday - as firefighters battled to contain the blaze. Thick plumes of smoke could be seen billowing into the sky after the fire broke out at around 10pm on Wednesday, with the inferno continuing to rage on throughout today. Footage released by the Derby Mountain Rescue Team show the scale of the blaze, which has now scorched 400 square metres of land amid tinderbox conditions caused by the unprecedented heatwave.Derbyshire Fire and Rescue Service said six fire crews were at the scene today, while helicopters were drafted in to throw water on the inferno from above. The wildfire comes as Britain swelters under a 'heat dome' - with temperatures reaching 36.7C this afternoon, just one day after Gosport in Hampshire hit 36.1C, breaking the record set in 1976.Temperatures are expected to soar again tomorrow to 38C, or 36C in the shade - as swathes of England and Wales remain under a rare red warning for extreme heat. Footage captured by the Derby Mountain Rescue Team shows the scale of the blaze, which has now affected 400 sq m of land A helicopter flies above a wildfire as burns near a forest in Glossop near Wood Head Reservoir, Derbyshire Thousands of people cool off in the sea in Bournemouth, Dorset, this afternoon A helicopter throws water above a wildfire as it burns near a forest in GlossopThe Met Office said it had extended a rare red extreme heat warning for 'population-wide adverse health effects' and a 'danger to life' by another day until tomorrow.South East England will remain under the warning, which was previously issued for yesterday and today.A major search is currently underway for a teenager who was last seen entering a popular lake to go swimming.Emergency services descended on Meynell Lake in Syston, Leicestershire to look for the boy just after 1.30pm on Thursday.It comes after a swimmer died after going into the sea during a visit to Aberavon beach in Port Talbot, South Wales, at about 4.30pm yesterday.Coastguard personnel performed CPR but the 50-year-old man from nearby Cilfrew died at the scene.Elsewhere a fire engine caught fire in the heatwave while travelling to a crash on the A350 at Charlton Marshall in Dorset at 6.30pm yesterday.The crew from Blandford fire station stopped the vehicle and managed to escape before calling for backup.Two other crews from Wimborne and Sturminster Newton rushed to the scene to tackle the inferno which burnt out the engine's cab – and the fire also spread to the nearby grass verge and telegraph cables before it was eventually put out by 8.30pm. The blaze caused the engine's tyres and cylinders, including breathing apparatus sets, to explode.Last night was also the UK's warmest June night ever after overnight temperatures in Cardiff failed to drop below 23.5C, beating the previous record of 22.7C in 1976. Residents on a street in Hanwell, London, have put up tin foil to help during the searing heat Spectators sit back in sun loungers at the Eastbourne Open tennis tournament today Pictured: The Pimm's Punt Bar serving drinks along the River Cam in Cambridge People queue to get their hands on an air conditioning unit from a Lidl in Southampton todaySchools and nurseries across swathes of England and Wales have either closed or partially closed, with some bringing in early finishing times or relaxed uniform rules.At least 1,600 schools in England and 840 in Wales were closed or disrupted during this week's heatwave, according to analysis of council websites by BBC News.In Guernsey, La Houguette Primary School helping pupils keep cool by moving some lessons to a Nazi bunker built when the island was occupied during World War Two.Transport networks have faced major disruption and people are being urged to stay inside between 11am to 3pm, close windows and curtains and stay hydrated.South Western Railway passengers have been urged to avoid non-essential travel to seaside resorts such as Bournemouth tomorrow because of the heat.Portsmouth's Queen Alexandra Hospital declared a critical incident following a failure to its cooling system supporting 'critical infrastructure', as did Norfolk and Norwich University Hospitals NHS Trust after its MRI scanners stopped working in the heat.King Charles III was among those feeling the heat yesterday at a reception on climate change at St James's Palace in London, which does not have air conditioning.As he greeted delegates in the throne room, His Majesty was wafted with an electric fan held by Vice Admiral Sir Tony Johnstone-Burt , Master of the Household. A woman uses a fan to cool down during the extremely hot weather in London today A fire engine caught fire while travelling to a crash at Charlton Marshall in Dorset yesterday Supermarket freezers have been stripped almost bare as Brits try every way they can to keep coolMore than ten people were taken to hospital mostly for heat-related illnesses after a collision on the M25 in Surrey which caused long queues in unbearable conditions.The BBC urged staff to avoid coming into the office, with an email 'recommending that you consider working from home if you are in an area covered by the warning'.London Mayor Sir Sadiq Khan also told ITV News: 'I think all of us need to be aware this is dangerous. If you can, work from home, and it's cool, working from home.'And in Hampshire, Testwood Lakes near Totton in Southampton was closed off to the public as police marine units joined other emergency services to search for a 15-year-old boy reported missing after last being seen swimming at 1.35pm yesterday.London Ambulance Service responded to 642 category one calls yesterday – the highest number of life-threatening emergencies in its history.Category one calls include the most serious, life-threatening injuries and illnesses such as cardiac arrests and patients who are not breathing.Chief executive Jason Killens KAM said: 'We have seen the highest number of life-threatening emergencies in our history, driven by the extreme heat across London.'Our crews are working very hard in challenging conditions to care for patients and I would like to take this opportunity to thank all our people for their incredible hard work. Please help them to help you by taking care of yourself and others – stay out of the sun and keep hydrated.'It was the fifth busiest day in the service's history, with 7,900 calls in total and ambulance crews responding to nearly 3,600 patients in a single day.