After facing months of siege and 20,000 Iraqi government troop, ISIS fighters in Fallujah reportedly are stopping people in streets and breaking into homes to force them to give blood for their wounded fighters. Witnesses shared ISIS militants are leaving some people drained and dying.

"ISIS now have a large number of wounded fighters and is desperate for blood," an Iraqi source told Fox News. "Many of the civilians couldn't get even two meals a day for a long time, so they're very ill and weak."

Iraqi forces are attempting to retake the city without destroying it or worsening an escalating humanitarian crisis, according to military officials. Their door-to-door effort to free the city also is being slowed by the firepower of dug-in terrorists, reports Fox News.

"ISIS is using a lot of snipers and plenty of IEDs," Capt. Omar Nazar, head of an elite unit in the Iraqi Emergency Response Division, told Fox News. "They have booby-trapped a lot of homes and they are moving civilians around to use them as human shields."

Fallujah is Islamic State's key stronghold in Iraq. This city of 300,000 was the scene of some of the bloodiest urban combat with U.S. forces in 2004. ISIS took control of it two years ago.

Government forces, backed by U.S. airstrikes, pushed through three ISIS perimeters and killed regional ISIS commander Abu Amir Ansari. They also took control of the city's main hospital and a key bridge across the Euphrates. ISIS is repelling with car bombs, snipers and artillery, as well as stocking the front line with foreign fighters, reports military officials.

The United Nations estimates as many as 90,000 civilians could still be trapped inside the explosive city. Several have died in their attempts to escape, including some who drowned in makeshift rafts trying to cross the Euphrates.

An authorized official with the Saraya Al Ashura popular mobilization unit told Fox News they are committed to the human rights treaties and agreements:  "We conduct our operations as far away as possible from residential areas. We are not interacting with the civilian population and only fighting in close combat against ISIS so we don't have to use our rockets, which could cause severe damage to them."