A single fire was lit in the early hours of the morning, but by 11 a.m. local time, dozens of tents and shacks were ablaze -- a suffocating blanket of black smoke over the camp.
The fires followed several nights of clashes this week between police and migrants who refused to leave the camp, as French authorities began busing residents out by the thousands
and demolition teams started tearing the camp down.
"We had anticipated this by pre-positioning firefighters as part of this operation and also passed the message to migrants and community representatives not to set fire to the shelters," a Calais prefecture spokesperson said.
"The cleaning company will today continue the removal of empty shelters to limit the risk of further fires."
The Jungle has become a wretched symbol of Europe's migrant crisis, and France has tried to shut it down several times, only to be denied by the courts. Migrants have long refused to leave the camp, which sits some 30 miles across the Eurotunnel to the UK, one of the more desirable countries for refugees in the region.
Calais prefect Fabienne Buccio told reporters Wednesday that four Afghan migrants had been arrested in connection with the fires, and that authorities planned to have moved everyone out of the camp by the end of the day. Bulldozers would go in tonight to raze the settlement, she said.
"I think by the end of the week we will have a clear future vision for Calais going forward," she said.
'Trying to get to England'
A group of young volunteers from several countries, who have for the past three days stationed themselves to monitor for fires in the camp, rushed to the first large fire set Wednesday.
With no plumbing in the camp, they relied on small extinguishers and a hose attached to a water tank, and tore down surrounding tents to stop the fire from spreading.
The shelter had housed a group of Syrians, the activists said, explaining it had taken four days for volunteers to build.
Authorities had by Wednesday morning sent more than 4,400 migrants off to other parts of France to begin the process of resettlement. Calais prefecture officials said all of the camp's migrants will have been resettled by the end of Wednesday.
There are believed to have been up to 10,000 migrants in the camp before the process began Monday.
Many have refused to be settled in France, and have run away to try their chances on the streets of Calais.
Others are refusing to leave, still clinging on to hope that they will make it to Britain.
A 16-year-old Afghan was one of them. He came to the Jungle alone and has lived there for nine months. He doesn't want to stay in France.
He told CNN his name -- Hashoq -- but couldn't say how it was spelled.
"I never learned to write," he said.
"I go. Jungle finished," he said, but couldn't say where he planned to go.
"I'm here working, working, trying to get to England."