New details about the reported escape of women connected to Islamic State from a camp in northeast Syria suggest that dozens were taken by Turkey-backed rebels who may now be holding them for ransom.

Hundreds of female ISIS adherents and their children were said to have escaped from a secure section of Ain Issa camp on October 14 following a Turkish airstrike in the area. Initial reports said refugees fled the camp first, prompting the women to follow, while others claimed that Syrian Democratic Forces guards standing watch over the roughly 1,000 women and children in a secure annex of the camp opened the doors and told them to leave.

Until this week, Ain Issa camp was home to 13,000 people, most of them displaced by fighting in Syria’s eight-year-long civil war.

A source with an international humanitarian organization operating in the area told The Defense Post on Friday, October 18 that Turkey-backed forces invaded Ain Issa, and staff reported that “troops went to the area where foreign families were living and, without incident, took about 150 foreign families.”

They then set fire to the area and camp offices, before leaving with the families.

“This is only going to make a dire, dangerous situation even worse,” said the source, who requested anonymity to ensure the safety of humanitarian workers in northeast Syria.

A British woman from the camp, Tooba Gondal, told The Telegraph on Friday that she had left the camp on her own accord, had later met Syrian rebel fighters and was currently being held near the Turkish border.

Gondal provided photos suggesting she is being held by Ahrar al-Sharqiya, and The Telegraph reported that the Islamist rebel group is effectively holding a number of women for ransom in exchange for allowing them to be smuggled over the border into Turkey.

The humanitarian source told The Defense Post they were struck by how the fighters removed the women without incident.

The fate of most of the other foreign women and children remains unknown. Nine French women are believed to have escaped, the Independent reported on Wednesday. Three British orphans discovered at the camp by a BBC team have been rescued, and an Irish woman, Lisa Smith, is also believed to be in Ahrar al-Sharqiya’s custody. The Irish Times reported that someone claiming to represent the group was attempting to sell an interview with Smith.

The United Nations Children’s Fund (UNICEF) said on Thursday that Ain Issa camp was mostly empty and most residents had moved south to Mahmudli camp near Tabqa.

ISIS claimed on Thursday that it had freed women from Mahmudli, but there have been no substantiated reports of an escape.

Aid organizations including the U.N. are now operating in northeast Syria with limited staff and the humanitarian situation is dire for nearly 200,000 people who have fled their homes since Turkey’s incursion began on October 9.

Furthermore, many of the organizations destroyed their files and equipment as they left the camps, the humanitarian source said, in order to ensure the protection of both their staff and displaced people.

The Syrian Arab Army, which entered many parts of the north on earlier this week following a military agreement with the SDF, has established checkpoints and staff are afraid to travel, concerned they will be conscripted into the army, the source said.

Ahrar al-Sharqiya is one of the groups fighting the SDF in northern Syria under the banner of the Syrian National Army. The rebels have been accused of serious violations, including possible war crimes, after posting videos showing executions on the M4 highway which traverses northeast Syria. They have also admitted to the execution of a Kurdish politician, Hevrin Khalaf, on the same road.

Fighting between the SDF and Turkey-backed groups in Ras al-Ayn continued on Friday despite a 120-hour ceasefire announced the previous night by U.S. Vice President Mike Pence following a meeting with Turkish President Recep Tayyip Erdogan.

Under the terms of the agreement, and according to previous statements by U.S. President Donald Trump, Turkey is supposed to be responsible for the thousands of ISIS fighters and their families in custody throughout northeast Syria. That responsibility had been the burden of the SDF and its internal security services, who warned that they could not ensure the security of ISIS prisoners if Turkey invaded.