The Pentagon says the U.S. military is now unlikely to attempt a rescue mission for the Yazidi minorities trapped on Iraq’s Sinjar Mountain, because so few are left. One reason why: ISIS has taken hundreds, if not thousands, of Yazidis prisoner, and threatened them with slavery and rape. But a few of the prisoners have smuggled in cellphones and are reaching out—pleading for help.

In desperate phone calls to relatives in Iraq and in the U.S., they’re begging for rescue from the prisons, schools or mosques across northern Iraq, where they are being held by ISIS militants.

They all tell a similar tale of horror: families fleeing on foot caught by militants in trucks and cars. The men are then dragged away at gunpoint from their wives and children, never to be seen again. The younger unmarried women are being told they will be forcibly married to ISIS fighters. Some are taken away and raped and a few have even been sold at Mosul’s main market.

The married women aren’t sure what will happen to them and their children—they fear they will be sold into slavery.

“My sister and her children are terrified,” said Iraqi Yazidi Faisal Fhaqooli, speaking from Lincoln, Nebraska, on Wednesday.

His sister was able to hide her cellphone when ISIS fighters in trucks captured her family and hundreds of others when they were trying to flee the Sinjar area on foot.

She said militants dragged her husband away, and took her and her children to a prison in Mosul over the weekend. On Tuesday, they were moved to a school in a nearby Iraqi city. (The Daily Beast is withholding certain specifics of their capture because of concerns for the prisoners’ safety.) She estimated there were up to a 1,000 women and children with her.

The Daily Beast could not independently verify her story, but it matches accounts given by other Yazidis fleeing the fighting, and was grimly confirmed by an unnamed ISIS commander who told CNN on Wednesday that his forces seized families, capturing the women and children, and killing the men. (He put the numbers at roughly 100 captives, not a thousand, however.)

Their plight shows the scope both of what Islamic State militants are willing to do to a civilian population that refuses to convert to their firebrand version of Islam, and also the breadth of the security problem faced by President Barack Obama as he weighs how many U.S. resources to commit to a new conflict in Iraq.

Obama had already authorized air drops of food and water for thousands of Yazidis who were trapped by ISIS fighters on Sinjar Mountain, while launching drone and jet missile strikes against the fighters below.

Pentagon spokesman Rear Adm. John Kirby said Wednesday evening that a small team of 20 U.S. special operations officers and USAID officials visited the site to assess how best to free those trapped there, but decided there were too few Yazidis left to merit a rescue mission. “The team has assessed that there far fewer Yazidis on Mount Sinjar than previously feared,” Kirby said in a statement Wednesday. “The Yazidis who remain are in better condition than previously believed and continue to have access to the food and water that we have dropped. Based on this assessment, the interagency has determined that an evacuation mission is far less likely.”

The American military team is part of the 130 U.S. Marines and special operations officers authorized by Obama on Tuesday to join the humanitarian effort, in addition to the roughly 900 U.S. troops already on the ground who are either advising Iraqi and Kurdish troops or protecting U.S. diplomatic personnel.

The Yazidis who have been captured have been reaching out to relatives and local news media, in hopes of expanding the U.S. mission to free ISIS’s Yazidi prisoners. But U.S. officials have said Kurdish and Iraqi forces must lead any attempts to take back territory—and free those captured—by ISIS militants.

Kurdish journalist Narin Shamo said she is in contact with Yazidi women being held in a prison in Mosul and others in the northern Iraqi city where Fhaqooli’s sister is being held. Speaking by phone from Northern Iraq on Wednesday, she said the younger women tell similar stories of being threatened with forced marriage, or being gang-raped and then returned back to their cells.

She said she and other community activists are trying to compile lists of names and locations of the captured Yazidis, to pass them on to Iraqi and U.S. officials, in hopes of rescuing them.

German-based Yazidi activist Raid Abo said by email that he had reports that 70 to 100 families had been captured and jailed around the same time and location as Fhaqooli’s sister.

According to Fhaqooli’s sister, describing when they were first captured, the ISIS fighters told the families they would be reunited with the men later, but she still fought being separated from her husband and being put on a truck, so the militants shoved her roughly into the vehicle.

She said she stopped fighting when the militants shot and killed a heavily pregnant woman who refused to get on the trucks.

She believes her husband is dead.

When the group reached the Mosul prison, she said, the ISIS fighters separated them into three groups: older women, younger women and girls, and then boys. She described the older women being taken away, their fate unknown, but said the mothers nearly rioted first when the fighters tried to take the boys, and later when they came for the younger unmarried women.

“So now they are taking the boys a few at a time,” Fhaqooli said, every time they come back to wherever the women and children are being held.

The group is getting limited food and water, but aren’t being told what will happen to them. For now, all they can do is call their loved ones—and cry out for a rescue.