Two firefighters were killed and nine injured when a fireworks factory exploded in flames.
The victims, one fire officer and one member of the fire support team, were among emergency services teams sent to tackle a blaze at the Festival Fireworks factory at Shortgate, near Lewes.
East Sussex Fire and Rescue Service said one of those killed was a 49-year-old control room staff member who was also a retained fire officer.
The other was a 63-year-old retired fire officer who had been re-employed and provided support at incidents.
Retired firefighter and brigade photographer Brian Wembridge lost his life doing something he loved dearly, said a colleague He said: "When I first saw the news announced a chill went up my spine and I worried that it was Brian.
"He was such a nice guy - you could not say a bad thing about him.
"He wouldn't harm a fly, was great to talk to and was a good laugh. Most importantly he was dedicated to East Sussex Fire and Rescue Service.
"He had been a firefighter for many years and he loved the work he did. But sometimes there is a risk in what we do. There is that element of danger.
"Many, many people would have seen his work in the papers and on TV. He will be sadly missed by everybody."
The news of the deaths was broken to the families by East Sussex Chief Fire Officer Desmond Pritchard.
A police sergeant and two members of the public were also hurt in the explosions.
Ten people were evacuated to safety from nearby homes and businesses.
Witnesses said the area was rocked by a series of blasts after the fire started yesterday afternoon.
The explosions sent debris flying through the air and caused nearby buildings to shake.
Five hours after the first emergency calls, fireworks were still exploding from the wreckage.
Sussex Police Assistant Chief Constable Jeremy Paine said: "There is a 200 metre cordon around the factory.
"The advice from the Fire and Rescue Service is that the fire needs to be allowed to burn for a while because of health and safety concerns around acetylene tanks that may be present."
People felt the explosions up to six miles away. Shoppers at Tesco in Uckfield froze in fear as the blasts rocked the store while people in Horam said their homes shook.
A mushroom cloud of smoke could be seen for miles around the blazing building.
A Sussex police coroner's officer was at the scene last night, along with a police chaplain.
Lewes MP Norman Baker said: "It is a terrible event and I feel deeply sad for the families that have lost firefighters.
"It is always sad when someone dies but particularly when they are serving other people and part of the emergency services and essentially putting their lives on the line for other people."
The emergency services declared a major incident and casualties were taken to hospitals in Brighton and Eastbourne.
Janine Bell, of South East Coast Ambulance Service, said: "We declared this as a major incident." She added that the situation worsened during the afternoon.
Jim Parrott, South East region secretary for the Fire Brigades Union, said: "We are extremely sorry for the loss and feel for the families of the two firefighters.
"We will take every step to co-operate with the East Sussex Fire and Rescue Service in their investigations."
He added that the union would provide every support for colleagues of the two firefighters.
Noel Tobin, Director of the National Campaign for Firework Safety, said: "This has been a very serious explosion and fire and calls into question the sort of fireworks we import from China into the UK, as the industry goes for a mostly import business.
"Just how much inspection and regulation for these factories is a question that has to be asked of the Health and Safety Executive.
"It is not enough to just go down and have a look and afterwards bury the report so that nobody is embarrassed."
Philip Thomas, of the Royal Sussex County Hospital in Brighton, said seven people had been admitted to the hospital, two with serious injuries.
He said: "They are both in a serious condition but are stable.
"One has had a blast injury, an injury to the chest, bleeding from the chest.
"We are aware that five of the injured are from the emergency services.
"The other five people are all conscious and undergoing treatment for a variety of burns and limb injuries.
"None is in a serious condition but they will remain in hospital tonight."
Eastbourne District General Hospital received five casualties, four of whom were later discharged.
A fifth casualty was expected to be kept in overnight but did not suffer life-threatening injuries.
The drama began shortly before 2pm when emergency services were alerted to the blaze.
Witnesses said the biggest explosions took place up to an hour after the fire started.
Richard Mitchell, 30, a roofer, watched the drama unfold from outside The Anchor Inn pub, in Lewes Road, Ringmer.
He said: "It was like a fireworks display with a fire in the middle of it. It was manic." John Davies, of The Black Lion pub in nearby Halland, said customers felt the building shake when the fireworks started exploding.
He said: "The noise just kept getting louder and louder. About three o'clock was the loudest bang. It actually shook the pub and probably most of the houses in the village."
John Winter said his brother, who owns the fireworks factory, fled the burning building with his sons. He said there had been "an almighty bang, and the place shook". Mr Winter said the storage buildings, made of concrete with reinforced steel doors, exploded as the fire spread.
A house had been destroyed, nearby properties damaged by flying tiles and glass, and a nearby restaurant evacuated.
Asked if there were a lot of fireworks in storage, he said: "There is still quite a bit there. We have just got over Bonfire Night so that got rid of a lot.
"There is still a few left for New Year and over Christmas. But they have all gone now."
Asked about how the fire started, he said: "There was an almighty bang and the whole place shook and that was it.
"Ever since it started, each shed and each storage place has blown up as it has gone along.
"The buildings have to be reinforced with concrete and steel and steel doors, all sorts of things."
He added: "It could have been an electrical fault in the house or one of the sheds - anything. You just don't know."
Mr Winter's nephew Jason said the family had lost everything, including their pets, a dog and a guinea pig.
A family-run company, Festival Fireworks employs around 50.
It is one of the biggest firework importers in the UK and stages firework spectaculars in Britain and abroad.
High profile shows included the Millennium display alongside the River Thames, the Queen Mother's birthday and the Lord Mayor's Show in London.
An investigation has been launched by the fire service, police and health and safety officers into the cause of the blaze.
Go to our photo gallery of the inferno.