As U.S.-led airstrikes continued to take down Islamic State group fighters this week, the extremists reportedly forced Syrian civilians to donate blood for their wounded. Up to 100 residents of Raqqa, the ISIS capital in eastern Syria, were required to get blood drawn at the city's private hospitals, according to the Independent. Most were men.

“Forcing civilians to donate blood is prohibited and inhuman, especially since the IS group does so randomly, regardless of the type of blood,” al-Quds al-Arabi newspaper reporter Jiwan Soz told ARA News. "The group is drawing blood in a primitive way without using the medical tools necessary for this process."

Blood transfusions in Raqqa used to be voluntary and even popular at one point when bombs were hitting civilians in 2014. But this recent blood drive was mandatory, motivated by the need to care for militants hurt by airstrikes in Kobani, Syria, and battles with Kurdish fighters near Mosul, Iraq, according to the Independent. There have also been reports of female Yazidi hostages being forced to give blood.

"They even take our girls' and old women's blood," Yazidi activist Nareen Shammo told the Independent. "They use it for their wounded ISIS fighters."

The extremist organization has been treating its members in private hospitals, so it's difficult to estimate death tolls. Reuters reported that at least 20 ISIS fighters died Thursday, and since August, U.S.-led coalition bombs have killed about 7,000 ISIS militants. The CIA estimated last year that ISIS' membership in the Middle East was between 20,000 and 31,500.

"We will continue to fight this war until we have achieved its goal, wiping ISIS from the face of the Earth," Maj. Gen. Mansour Jabour of the Royal Jordanian Air Force told the Washington Post.

In addition to the U.S., Australia, Belgium, Canada, Denmark, France, Netherlands and the United Kingdom are dropping bombs in Iraq. Coalition countries conducting airstrikes in Syria include the U.S., Bahrain, Jordan, Saudi Arabia and the United Arab Emirates, according to the U.S. Department of Defense.