Calais, France (CNN) Tensions are high inside "The Jungle," a sprawling makeshift refugee camp in the French port town of Calais, where authorities are to begin evicting migrants Monday.

Authorities have given the thousands of people living there two options: seek asylum in France or return to their country of origin.

Some 6,900 refugees, more than 1,200 of them children, live in the encampment, a jumble of squalid tents and temporary shelters.

Clashes between migrants and police erupted Saturday night at the camp, said Sue Jex, head of operations for the charity Care 4 Calais. She said a number of buildings inside the camp were destroyed by fire.

By Sunday night, CNN counted at least seven vans loaded with riot police, armed with tear gas, arriving on the scene.

On the outskirts of the camp, migrants gathered around small fires on the gravel path and in a dumpster. One person taunted a group of police officers near one of the small fires and attempted to film them on his mobile phone. Police charged toward him until he backed off and moved away. At least six small fires were spotted within the camp and its outskirts.

A large number of police are on hand to prevent crowd problems. More than 1,000 riot police officers were deployed to the camp Sunday ahead of the closure, an Interior Ministry spokesman told CNN. Horse-mounted police were seen near the camp.

"It's very tense because people know that change is coming," Jex told CNN. "There is a real acceptance that the camp is going (away)."

The plan is to have the camp completely torn down by December, according to the Interior Ministry. The camp sprawls over about 40 acres of sand dunes once used for landfill, with different nationalities in different sections.

Many in "The Jungle" are reluctant to register as refugees in France because their preferred destination is Britain.

"I try to stay in England but I don't have money to go in England or to stay in France. I think it is so hard for me, it is not easy ..." one Sudanese migrant said. "Only God can help me right now."

A volunteer French teacher at a school in the camp said people are worried because they do not know where they will go.

"They have no idea which place they're headed to and above all if they are going to stay with their friends," said Michel Abecassis. "We are all very worried, I am very worried. A lot of people are here with very close friends and of course their hope is to be in a reception center with their friends, and not to just be sent anywhere."

Photos: The saga of the Calais 'Jungle' French authorities stand by as migrant minors board a bus to relocation centers on October 28. Authorities began work on Monday to clear the infamous migrant camp known as the Calais "Jungle" in northern France. Hide Caption 1 of 64 Photos: The saga of the Calais 'Jungle' A young migrant stands outside the Calais camp school house on October 28. Minors who were not moved to safe houses outside of the Jungle earlier in the week were let back into the camp to shelter in the makeshift school for the night.

Hide Caption 2 of 64 Photos: The saga of the Calais 'Jungle' A trailer burns in the Calais "Jungle" early on Friday, October 28. Hide Caption 3 of 64 Photos: The saga of the Calais 'Jungle' Riot police guard the main entrance to the Jungle on Thursday, October 27. Authorities have declared the camp clear, but aid workers say that up to 100 unaccompanied minors remained with nowhere to sleep. Hide Caption 4 of 64 Photos: The saga of the Calais 'Jungle' A migrant man sits inside a shack that remains in the otherwise demolished Jungle camp on October 27. French authorities said Wednesday that almost 5,600 migrants had been bused to relocation centers around France. Hide Caption 5 of 64 Photos: The saga of the Calais 'Jungle' Heavy machinery is used to remove debris from the camp on October 27. Hide Caption 6 of 64 Photos: The saga of the Calais 'Jungle' An Eritrean migrant waits to be relocated out of the camp on October 27. French authorities have given thousands of people who were living in the infamous migrant camp two options: seek asylum in France or return to your country of origin. Hide Caption 7 of 64 Photos: The saga of the Calais 'Jungle' A migrant shaves while cleaning crews continue demolition of the Jungle on October 27 Hide Caption 8 of 64 Photos: The saga of the Calais 'Jungle' A group of migrants who slept outside an aid station near the Jungle wait to be assigned relocation to processing centers across France on October 27. Hide Caption 9 of 64 Photos: The saga of the Calais 'Jungle' Two migrants rest near the Jungle site on October 27. Long lines for processing have been cited as the reason some didn't manage to register earlier in the week. Hide Caption 10 of 64 Photos: The saga of the Calais 'Jungle' Smoke rises from multiple fires blazing in the camp on Wednesday, October 26, as French authorities work to demolish the settlement and evacuate its residents to reception centers around France. Hide Caption 11 of 64 Photos: The saga of the Calais 'Jungle' A French fireman attempts to extinguish a blaze in the Calais Jungle on October 26. Hide Caption 12 of 64 Photos: The saga of the Calais 'Jungle' Remaining migrants watch fires burn across the Jungle on October 26. Migrants set fire to structures along the camp's main street. Hide Caption 13 of 64 Photos: The saga of the Calais 'Jungle' The remains of makeshift structures smolder from fires that broke out overnight in parts of the camp on October 26. Hide Caption 14 of 64 Photos: The saga of the Calais 'Jungle' A man looks skyward as he stands beside the burned remnants of his tent in the Jungle on October 26. Hide Caption 15 of 64 Photos: The saga of the Calais 'Jungle' A migrant walks past a burning shack that was set on fire, as a demolition crew began tearing structures down on Tuesday, October 25. Hide Caption 16 of 64 Photos: The saga of the Calais 'Jungle' Women and children protest their case to the UK government from the Jungle, as authorities continue the destruction of the camp on October 26. Hide Caption 17 of 64 Photos: The saga of the Calais 'Jungle' French authorities stand guard after migrants set fire to a shelter during the dismantling of the Calais "Jungle" camp on October 25. Hide Caption 18 of 64 Photos: The saga of the Calais 'Jungle' Workers begin demolishing shelters in the camp on October 25. Hide Caption 19 of 64 Photos: The saga of the Calais 'Jungle' A volunteer helps a man carry his luggage away from the camp on October 25. Hide Caption 20 of 64 Photos: The saga of the Calais 'Jungle' French demolition teams work to dismantle the camp on October 25. Hide Caption 21 of 64 Photos: The saga of the Calais 'Jungle' A police officer guards demolition crews as they work to dismantle the site on October 25. Hide Caption 22 of 64 Photos: The saga of the Calais 'Jungle' A man passes a camp structure on fire on October 25. Hide Caption 23 of 64 Photos: The saga of the Calais 'Jungle' A firefighter extinguishes a fire set to migrants' tents during the mass evacuation. Hide Caption 24 of 64 Photos: The saga of the Calais 'Jungle' Women arrive at a meeting point determined by authorities managing the evacuation of the camp. Hide Caption 25 of 64 Photos: The saga of the Calais 'Jungle' Migrants' belongings are trucked out of the "Jungle" on October 25. Hide Caption 26 of 64 Photos: The saga of the Calais 'Jungle' Sudanese migrants wait in line to board buses that will take them to relocation centers across France. Hide Caption 27 of 64 Photos: The saga of the Calais 'Jungle' People walk through the camp on October 25. Hide Caption 28 of 64 Photos: The saga of the Calais 'Jungle' A migrant sets fire to a portable toilet inside the camp on Monday, October 24. Hide Caption 29 of 64 Photos: The saga of the Calais 'Jungle' Police try to maintain order as migrants waiting to be processed wait in crowded lines on October 24. Hide Caption 30 of 64 Photos: The saga of the Calais 'Jungle' Migrants leave their makeshift homes on October 24. Hide Caption 31 of 64 Photos: The saga of the Calais 'Jungle' Migrants register with French authorities on October 24 before boarding buses that will transport them to shelters across France. Hide Caption 32 of 64 Photos: The saga of the Calais 'Jungle' Migrants board buses that will transport them to shelters around France on October 24. Those applying for asylum will be offered temporary accommodation in a shelter while their claim is processed. Hide Caption 33 of 64 Photos: The saga of the Calais 'Jungle' Residents of the camp hug before departing the "Jungle" on October 24. Hide Caption 34 of 64 Photos: The saga of the Calais 'Jungle' Men, women and children leave the camp during the first day of the planned eviction on October 24. Hide Caption 35 of 64 Photos: The saga of the Calais 'Jungle' Riot police stand off with some of the camp's residents the night before the eviction was set to take place. Hide Caption 36 of 64 Photos: The saga of the Calais 'Jungle' French police fire tear gas after refugees reportedly threw rocks at police vans near the camp on Saturday, October 22. Hide Caption 37 of 64 Photos: The saga of the Calais 'Jungle' A view of the migrant camp in Calais on Wednesday, October 12. Hide Caption 38 of 64 Photos: The saga of the Calais 'Jungle' Refugees in Calais claimed their rights to pass to Great Britain but were pushed back by tear gas and flash grenades on Saturday, October 1. Hide Caption 39 of 64 Photos: The saga of the Calais 'Jungle' Migrants walk past security fencing on Tuesday, September 6. Hide Caption 40 of 64 Photos: The saga of the Calais 'Jungle' French business owners and local residents block the main road into the Port of Calais as they protest "The Jungle" on Monday, September 5. Hide Caption 41 of 64 Photos: The saga of the Calais 'Jungle' This aerial view taken Tuesday, August 16, shows the tents and shipping containers housing migrants in "The Jungle." Hide Caption 42 of 64 Photos: The saga of the Calais 'Jungle' A French riot policeman stands near graffiti during the dismantling of the southern part of "The Jungle" migrant camp on Thursday, March 10. The graffiti reads "London calling," a reference to how the camp has become notorious for migrants and refugees trying to enter the UK illegally. Hide Caption 43 of 64 Photos: The saga of the Calais 'Jungle' A man sews the lips of an Iranian migrant at the camp on Thursday, March 3. Journalists said at least nine Iranians stitched their mouths shut and went on a hunger strike to protest the camp's dismantling. Hide Caption 44 of 64 Photos: The saga of the Calais 'Jungle' Migrants stand next to a burning shack in the camp on Tuesday, March 1. Hide Caption 45 of 64 Photos: The saga of the Calais 'Jungle' A migrant makes a phone call near "The Jungle" on March 1. Hide Caption 46 of 64 Photos: The saga of the Calais 'Jungle' A woman fights with a police officer as she is removed from the top of a hut on March 1. Police and demolition teams were starting to dismantle makeshift shelters and relocating people to accommodations nearby. Hide Caption 47 of 64 Photos: The saga of the Calais 'Jungle' Migrants demonstrate on Monday, February 29. Hide Caption 48 of 64 Photos: The saga of the Calais 'Jungle' Riot police spray water on migrants to disperse them during the dismantling of half of "The Jungle" on February 29. Hide Caption 49 of 64 Photos: The saga of the Calais 'Jungle' A migrant flies a kite on Friday, February 19. Hide Caption 50 of 64 Photos: The saga of the Calais 'Jungle' Migrants walk past housing containers in "The Jungle" on Tuesday, February 16. Hide Caption 51 of 64 Photos: The saga of the Calais 'Jungle' Two young boys walk in the mud inside "The Jungle" in December 2015. Hide Caption 52 of 64 Photos: The saga of the Calais 'Jungle' A man is seen among tents in "The Jungle" in October 2015. Hide Caption 53 of 64 Photos: The saga of the Calais 'Jungle' French police oversee the removal of tents in September 2015. Hide Caption 54 of 64 Photos: The saga of the Calais 'Jungle' Afghan and Pakistani migrants eat lunch in the migrant camp in August 2015. Hide Caption 55 of 64 Photos: The saga of the Calais 'Jungle' Migrants walk along the railway track leading to the Eurotunnel in Calais in August 2015. Migrants attempt to enter the UK illegally by stowing away on trucks, ferries, cars or trains. Hide Caption 56 of 64 Photos: The saga of the Calais 'Jungle' A migrant hides on the train tracks in the direction of the Eurotunnel terminal in August 2015. Hide Caption 57 of 64 Photos: The saga of the Calais 'Jungle' The home of Sami, a refugee living in the "The Jungle," is pictured in August 2015. Sami, who has lived in the camp for two months, said: "We made this house from blankets and wood and then covered it in plastic to keep the rain out. It rains often in France. I think it will rain often when I am in England, too." Hide Caption 58 of 64 Photos: The saga of the Calais 'Jungle' Several migrants successfully cross the Eurotunnel terminal in July 2015 as they try to reach a shuttle to the UK. Hide Caption 59 of 64 Photos: The saga of the Calais 'Jungle' Displaced from "The Jungle" camp, Afghan migrants congregate in Calais' harbor in September 2009. Hide Caption 60 of 64 Photos: The saga of the Calais 'Jungle' A digger lifts a migrant's makeshift tent during a destruction operation in September 2009. Hide Caption 61 of 64 Photos: The saga of the Calais 'Jungle' An aerial view of the camp in September 2009. Hide Caption 62 of 64 Photos: The saga of the Calais 'Jungle' Migrants from Afghanistan look at a ferry boat in Calais in September 2009. Hide Caption 63 of 64 Photos: The saga of the Calais 'Jungle' Migrants jump onto the back of a UK-bound truck in March 2006. Hide Caption 64 of 64

On Sunday, foot patrols of volunteers distributed flyers explaining that the camp is to close and outlining the two options open to its occupants: seek asylum in France and be relocated within the country, or return to their country of origin.

Authorities say residents of the camp will be processed on a first-come, first-served basis beginning Monday at 8 a.m. local time.

Residents were given a letter Sunday, translated into several languages.

The letter, obtained by CNN, tells the residents to make their way to a reception point where they will be put on buses.

"Everybody living in the Calais jungle will have to leave in order to be sheltered in one of the French reception and counseling centers," the letter said.

The letter assures migrants that they would be offered accommodation and meals.

Most of those living in the camp are from sub-Saharan Africa -- Sudan, Eritrea and Ethiopia -- and Afghanistan; they have spent months or even years there in the hope of reaching the UK, some 30 miles away across the English Channel. Refugees from war-torn Iraq and Syria have also set up temporary homes in the Jungle.

Those who choose to apply for asylum will be offered the choice of two French regions. They will be taken to the location they choose by bus almost immediately and offered temporary accommodation in a shelter while their claim is processed.

Up to 60 buses are expected to leave the camp on Monday, with dozens of further departures through the week.

Special provisions are to be made for unaccompanied minors.

The evacuation operation is expected to last a week, but a ministry spokesman told CNN: "If it takes more time, so be it. We have all the time in the world."

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Anyone who opts to go home will be taken there by plane.

Camp inhabitants who have already sought asylum elsewhere within the European Union will be transported to that country while their application is processed.

Cleaners are expected to begin work at the site on Tuesday, expanding their "cleaning zone" as the evacuation proceeds.

At a press briefing in Geneva earlier this week, UNHCR spokesperson Adrian Edwards said the closure was welcomed as long as the French government provided a suitable solution for the displaced. He noted that the lives of children would be particularly at risk during the demolition.

"This is important so that children don't move on to other destinations and risk becoming exploited by human traffickers or end up living on the streets without any support," he said. "Strengthened measures must be taken to reunite children with relatives in Europe."

The UN says 200 of the unaccompanied children in Calais have been identified as having family links to the UK. The British government has pledged to offer them a home, but only a handful have so far been taken to the UK.