The Islamic State group released about 200 Yazidis held for five months in Iraq, mostly elderly, infirm captives who likely slowed the extremists down, Kurdish military officials said Sunday.

Almost all of the freed prisoners are in poor health and bore signs of abuse and neglect. Three were young children. The former captives were being questioned and receiving medical treatment on Sunday in the town of Alton Kupri.

Gen. Shirko Fatih, commander of Kurdish peshmerga forces in the northern Iraqi city of Kirkuk, said it appears the militants released the prisoners because they were too much of a burden.

"It probably became too expensive to feed them and care for them," he said.

Tens of thousands of Yazidis fled in August when the Islamic State group captured the northern Iraqi town of Sinjar, near the Syrian border. But hundreds were taken captive by the group, with some Yazidi women forced into slavery, according to international rights groups and Iraqi officials.

The militants transported the mainly elderly captives from the northern town of Tal Afar and dropped them off Saturday at the Khazer Bridge, near the Kurdish regional capital of Irbil.

"Their situation is very bad, especially the psychological condition," said Hersh Hussein, a representative from the Irbil governor's office who was in Alton Kupri. "Regarding other diseases we provide first aid and the most important medical treatment."

Maha Faris Qassem, 35, was released with her two young sons, both of whom were covered from head to toe in bug bites which appear to be infected. She said the conditions of their captivity were so dire that infection was inevitable.

About 50,000 Yazidis -- half of them children, according to U.N. figures -- fled to the mountains outside Sinjar during the onslaught. Some still remain there.

The U.S. launched airstrikes and humanitarian aid drops in Iraq on Aug. 8, partly in response to the crisis on Sinjar mountain. Since then, a coalition of eight countries have conducted more than 1,000 airstrikes across Iraq in an effort to eradicate the IS group, which now holds a third of both Iraq and Syria.

The Sunni militant group views Yazidis and Shiite Muslims as apostates, and has demanded Christians either convert to Islam or pay a special tax.

"I don't know the details of why they released us," Gawre Semo, 69, told The Associated Press. "They are very bad people. They took our children and they took the women. They did bad things with us. We've been humiliated by them."