The pre-dawn queue out of the Porte de la Chapelle migrant camp snaked beneath Paris's massive ring-road. Hundreds of people waited to leave: their belongings stuffed into back-packs and shopping bags, their children wrapped in blankets against the rain.
By the time offices opened here on Thursday, more than 1,600 people - around half the area's migrant population - had been loaded on to buses and taken to shelters to be processed.
Many, like Muhammad who moved here from Afghanistan, said they were glad to leave their cold, wet, sometimes violent home for a few nights in a shelter.
"It's a good reaction," he said. "We're very happy about the French government. They help us, give us food, it's good."
But the prospect of being registered, processed and possibly deported by the French authorities meant some residents fled before the buses had even arrived.
One woman from Ethiopia told me before police moved in that she had come to France after being rejected several times by another EU country.
"It wasn't really my choice to come to France, but I heard it was better here," she told me. "And I saw a programme about the football team. It seemed that France was an international country, with more black people."
She wasn't in the camp on Thursday morning.
Read more from Lucy on France's migrant issue
"It's clear that for people who have already had their asylum claims rejected, or for the 'Dublin' people things will become much harder," said Yann Manzi, who heads the migrant organisation Utopia56. Under the EU's Dublin Regulation, anyone seeking asylum should be considered in the first member state in which they arrive.
He believes the police operation will mean more people trying to reach the UK via camps in France's Channel ports.
"We've seen before that those who can't apply for asylum go to Calais, so we think this will intensify what's happening in Calais and Dunkirk."
There'll be a hunt for them, both in Paris and in Calais-Dunkirk, so we can imagine that people will lose hope of staying here and will try the UK
The Paris clearance is the first strike in new tougher immigration policies, announced this week by French PM Edouard Philippe, including quotas for those with professional skills, a mass clearance of France's migrant camps, and restricted access to medical care for those who arrive here illegally.
"It's about sovereignty," the prime minister said. "We want to take back control of our immigration policy. Taking back control means ensuring that when we say yes, it's really yes. And when we say no, it's really no."
The government has vowed to clear all the major migrant camps in France before the end of the year.
Another operation is planned to evict the remaining areas of Porte de la Chapelle in Paris. Patrols have been brought in to make sure migrants don't return, as they have in the past.
The Paris camp grew so large partly because of a chronic lack of accommodation for migrants claiming asylum.
As part of its package of 20 measures to "take back control", the government has announced the creation of 16,000 more housing places, along with three more detention centres for those who remain here illegally.
The new policy is popular with many right-wing voters, but condemned as a PR stunt by some on the left.
President Emmanuel Macron's party is facing a duel with the far-right party of Marine Le Pen in local elections next year. Polls currently put them neck and neck.
Mr Macron was trying to win over Le Pen supporters, Yann Manzi told me.
But if he sails too close to the nationalist opposition, voters in future may decide they prefer the original.