CALAIS, France — After taking a group selfie, six underage migrants left the French city of Calais for Britain on Thursday, as both countries seek solutions for hundreds of unaccompanied children in the slum-like migrant camp known as the “jungle” before it is shut down in the coming weeks.

Concern about the children in Calais has mounted as France prepares to close the camp, a troubling symbol of Europe’s migrant crisis. One aid group estimates there are 1,300 unaccompanied minors in the camp, among between 6,000 and 10,000 migrants overall from across the Mideast and Africa and some Balkan countries.

Six happy and relieved youths — one Syrian, five Afghans — gathered in the Calais local administration headquarters Thursday morning before boarding a Eurostar train, accompanied by volunteers and French officials and clutching plastic folders of documents.

Britain’s Home Office says that small groups of children have been coming on a weekly basis for the last few months. Under pressure from France, the U.K. government said Monday it would begin admitting hundreds of children with relatives in Britain within days. However, questions remain about what will happen to those without family ties in the U.K.

“I’m very happy today … it was in my dreams” to reach Britain, said Saadi, a teen boy from Afghanistan. “In London, there is my family. My sister. We have to go. We don’t have any (other) solution.”

Among the other children was Mohammed Fadel Hani, a 14-year-old who had been working in a makeshift restaurant in the camp while hoping to reach Britain.

The director of aid group France Terre d’Asile, Pierre Henry, told The Associated Press that earlier this week it had counted about 1,300 unaccompanied minors among the Calais migrants, including about 40 percent who said they had relatives already in Britain.

Aid groups filed an emergency request this week with a court in Lille seeking to delay the closure of the camp, arguing that authorities aren’t ready to relocate its residents. Thierry Kuhn, director of aid group Emmaus, told The AP on Thursday that a decision is expected within 48 hours.

The government is gradually deporting migrants without right to asylum and relocating the rest to more than 160 centers around France. It is expected to close the camp in the coming weeks but no official dates have been announced.