More aerial pictures captured this morning show the heathland still burning heavily on the coastal site.

Currently about 90 firefighters are at the scene and 14 appliances, including fire trucks.

Suffolk Fire and Rescue Service says the response was initially scaled down to 70 firefighters before being escalated up again, going back to 90 before 08:00 BST.

Image source, Alex Tarry

Alex Tarry tells BBC Radio Suffolk's Johnnie Wright that he was jogging along the coast at Sizewell at 05:00 BST when he saw all the smoke behind the Coastguard Cottages at Dunwich Heath.

"I ran up there, there was a fire front that could have been half-a-mile long, about 150m away from me.

"The cottages were completely deserted but [the fire was] moving toward [them]."

Image source, Alex Tarry

He added: "It's very sad, a huge amount of heath is being affected.

"It's just absolutely shocking, it's coming closer and closer... I've known [Dunwich Heath] all my life and the wildlife, the history, the habitats has just been consumed.

"It was noisy with explosions, and bushes and trees were bursting into flames.

"There was just a feeling of there's nothing you can do and feeling utterly, utterly helpless... it's shocking."

Image source, Alex Tarry

Stav Danaos
BBC Weather

Image source, PA Media

Prolonged dry weather and recent heatwaves are leaving large areas of vegetation across the area exceptionally dry, creating ideal conditions for wildfires to spread once ignited.

Heathland, grass, shrubs and woodland that would normally contain some moisture have now become highly flammable after weeks of little or no rainfall.

Moderate winds are also playing a significant role, helping the fire to spread rapidly across Dunwich Heath.

Fire crews are describing the incident as a wind-driven wildfire, with the exceptionally dry landscape allowing flames to move quickly and making efforts to contain the blaze more difficult.

The wildfire comes after Suffolk was among the areas of England officially declared to be in a drought.

While the drought did not necessarily cause the fire to start, it created the conditions for any ignition to develop into a much larger, more intense fire.

The combination of dry vegetation, low soil moisture and windy conditions have significantly increased the risk of large and fast-moving fires across the region.

However, the ignition that started the fire was most likely human caused – accidental or deliberate - and is still under investigation.

As the fire spread, Suffolk Fire and Rescue Service said it had been working to protect properties including Coastguard Cottages, Mount Pleasant Farm and Cliff House Holiday Park, all of which were evacuated overnight.

The fire service confirmed 200 caravans had been evacuated, but the exact number of people affected is not known.

Zoie O'Brien
BBC Look East

Image source, Jamie Niblock/BBC

Paul Ashton is the deputy leader of East Suffolk Council, and says he has been told the fire is still not under control.

"That's what we've heard from the fire brigade," he says.

"They're still working hard to get it under control, so the people that are in Westleton that stayed here last night are waiting, really.

"They can't go back to get their possessions or their cars, so we're looking after them.

"The people of Westleton have done a sterling job, put people up last night, they've been fed with breakfast.

"I think there's plans for lunch as well, so they're all being looked after fine."

The district's MP Jenny Riddell-Carpenter says she has been receiving regular updates on the major incident, including speaking to Suffolk's chief fire officer this morning.

In a post on social media, she said: "I'm so grateful, as I know so many others are, for the work of the fire brigade and the emergency services."

The Suffolk Coastal MP urged residents in the smoke zone to follow the advice to keep their doors and windows closed.

The Labour politician also said "a huge thank you" to the residents who helped out evacuees.

Image source, Qays Najm/BBC

Luke Deal
BBC Radio Suffolk

Image source, Vikki Irwin/BBC

The fire has also spread to an area of RSPB Minsmere, which is next to Dunwich Heath.

Adam Rowlands, the Suffolk area manager for the RSPB, says "this is the biggest blaze we've seen at Minsmere, external in living memory", which has been "hugely consequential" for the local wildlife.

He says it could take up to 25 years for the heathland to return to the state it was in before the fire.

Rare species of butterfly would have been in the egg stage and birds were seen flying over fireballs.

Minsmere was previously the site where BBC Springwatch was filmed in 2014 for its 10th anniversary.

"Minsmere is a real jewel in the crown for the RSPB, many people will know it," Rowlands says.

"The heathland is incredibly important with some really rare wildlife... all of those bird populations will now be at risk.

"Most of them have finished breeding so they'll be able to escape the fire, and last night we could see nightjars flying above the fireball up on the heath.

"But the problem is it will look like a scene of devastation afterwards, all the vegetation will go and all those bird populations, the majority of them will lose the places where they nest.

"Some of that habitat will take five, 10, 25 years to come back to what it looked like before the fire broke out yesterday afternoon."

Vikki Irwin
BBC Radio Suffolk

Image source, Vikki Irwin/BBC

Archie, 16, from west London, was staying at his grandparents' caravan on the Dunwich Cliffs estate and helped evacuate the site.

He said he had been standing outside and spotted "a glow through the trees", and moments later a firefighter emerged.

"It was a bit too close for comfort but I wasn't panicked," he said.

"He asked me to help go around, knocking on doors telling people to prepare a bag in case they had to evacuate tonight."

He said he'd been coming to the site since he was a child and knew it well to navigate in the dark.

"I had to knock on everyone's doors. I had to get this woman and her two babies out of bed, get them in the car, an older woman, and get everybody out."

He said eventually he couldn't see 5ft in front of him due to how heavy the smoke was.

An equestrian centre for retired horses, just a mile from Dunwich Heath, says its staff were up most of the night ensuring the animals were safe and could be evacuated, if needed.

Dunwich Equestrian says in a statement, external some of the animals with asthma were moved elsewhere as smoke drifted over the centre, but they add that "not one of the horses really seemed to care that we were all running around after them".

"At 05:00 this morning I returned and fed everyone... we currently have no smoke but there's one hell of a smoke cloud drifting out to sea away from the village," they add.

Image source, Dunwich Equestrian

Footage from Wednesday evening shows fire crews tackling the blaze, which was destroying vast amounts of trees and greenery.

Vikki Irwin
BBC Radio Suffolk

Driving down the A12 at Marlesford towards Dunwich, I could see the dark smoke - the plume looked miles wide. Marlesford is at least 10 miles (16km) away.

As I got closer to Westleton Village Hall, there were towers of smoke towards the coast - you can smell the fire in the air.

At the village hall, volunteers turned out smiling and welcoming those who had to leave their homes or caravans in the night.

The village found beds for more than 40 people and hosted a breakfast for 60 this morning.

Evacuees grateful for the kindness have praised the village and those who have turned out to help when they were in greatest need.

Image source, Vikki Irwin/BBC

Alice Cunningham
BBC News, Suffolk

Our reporter Luke Deal has just spoken to Tara Dowsett from Chelmsford in Essex, who was on holiday at Cliff House Holiday Park close to the heath when the fire broke out.

She explained they had been driving back from Lowestoft on Wednesday night when they started to drive through "thick smoke", initially thinking it was an out-of-control bonfire.

"It was a real shock," she said.

She added that their dog, who they left at the holiday park, had to be rescued by police officers.

"It's scary, but I just want to give a big shout out to the people of Westleton because actions do speak louder than words," she continued.

"There's so much negativity in the world and you realise actually there are more kind people than nasty people."

Dunwich Heath is an area of coastal lowland just south of the village of Dunwich in Suffolk.

It is about 25 miles (40km) north-east from the county town of Ipswich.

Suffolk Fire and Rescue Service has urged people not to head to Dunwich Beach or anywhere else near the heathland "due to the ongoing nature and seriousness of the fire".

"We understand that the warm weather makes a trip to the coast very appealing, but for everyone's safety we are asking people to stay away from the area at this time," said a spokesperson.

"It is essential that the area and surrounding roads are kept clear to allow emergency services to carry out their work safely and effectively, and to help protect members of the public."

Three miles (4.8km) down the coast from Dunwich, the fire was clearly visible in Walberswick as the sun rose.

Image source, David Riches

Vikki Irwin
BBC Radio Suffolk

Colin Fisher, from Westleton Parish Council, has told me the response has been "truly amazing".

"A lot of people have turned out to do what they can where they can," he says.

"It's a hazard of living in an area where there's almost always a wind, and when you get an extended dry period like this, it's always a risk that there will be something of this nature that happens.

"In the past they tend to get put out quite quickly, but because of the dry weather, everything is a tinderbox."

Image source, Vikki Irwin/BBC

Footage captured at the scene shows the scale of the fire that crews are having to deal with.

The blaze comes as the UK Health Security Agency has issued an amber heat-health alert for the East Midlands, East of England, South East and London.

Suffolk is also among the areas of England where drought has been declared by the Environment Agency.

Droughts bring with them a high risk of wildfires, the agency warned.

Image source, Liz Quickenden

The Sizewell nuclear power station is about four miles (6.4km) down the coast from Dunwich Heath, as the crow flies.

Suffolk Fire and Rescue Service said: "At this time there is no current risk to Sizewell B, due to the distance from the fire and the direction it is travelling (easterly).

"However, this is a live and dynamic situation and as a result any further updates will be shared accordingly."