Calais 'Jungle': Overnight fires raze parts of migrant camp
At least one gas canister exploded, with one migrant lightly injured.
The clearance began on Monday and about 4,000 migrants - out of some 7,000 - have been taken from the squalid camp to shelters around France.
There remain concerns that some will refuse to give up their attempts to cross the Channel to get to the UK.
The operation has been largely peaceful so far.
The BBC's Simon Jones, at the camp, says huts were set on fire overnight on the main street leading into the camp, leaving them in ashes.
He says this may have been a last act of defiance from migrants who did not want to leave and did not want to see their shelters taken down by the authorities.
The prefect of Pas-de-Calais, Fabienne Buccio, told BFMTV is was "a tradition among the migrant population to destroy their homes before leaving".
However, the Calais police commissioner said he had been told by migrants that the fires were started by activists.
Camp resident Mahmoud al-Saleh told Agence France-Presse: "There were several fires overnight. Every time one was put out, another would erupt. It was clearly intentional.
"The firefighters came late. For a long time it was just us, migrants and volunteers, fighting the fires."
More smoke was seen rising from the camp on Wednesday morning.
More migrants joined queues on Wednesday for buses to take them out of the camp, with the situation calmer than the jostling of the previous morning.
Crews had begun dismantling the Jungle with sledgehammers on Tuesday. Workers in hard hats and orange jumpsuits pulled down unoccupied tents and shacks.
Source: bbc.com