Over 1,000 Iranian fighters have been killed in the Syrian war so far, Iran’s Tasnim news agency reported Tuesday, citing an official. The Syrian war, which began in 2011, has witnessed thousands of deaths and has displaced millions.

Mohammad Ali Shahidi, who runs the Martyr Foundation, said, “The number of martyred defenders of shrines… has passed the number of 1,000.” Shahidi’s Martyr Foundation provides assistance to families of troops who died fighting in conflicts.

He did not provide further details. He said in August this year that at least 400 troops sent from Iran to fight alongside Syrian President Bashar Assad’s troops were killed in the multi-faceted war. Half of those troops were Afghan.

The war in Syria began as a peaceful opposition movement to overthrow Assad and was inspired by the Arab Spring. It has since left over 300,000 dead. Over 4.8 million people have fled the country for Europe or neighboring Lebanon, Jordan and Turkey.

A Syrian monitoring group alleged Tuesday that rebel groups in Aleppo, once Syria’s largest city, are holding the city’s residents hostage to use as human shields. Repeated airstrikes over rebel-held eastern Aleppo has battered the city, killing scores.

Hajj Mohammed al-Jasim told the Associated Press his uncles’ families have been attempting to leave the rebel-held portion of the city but were unsuccessful.

“They’ve wanted to cross for a while because the circumstances have become very difficult,” he said. He added that his relatives who told al-Jasim that they would be fleeing the neighborhood during the day were advised by rebel groups to leave during the night instead.

“Then in the evening, [the rebels] began to fire at the crossing” preventing them from leaving, al-Jasim said. There are about 50 families waiting to leave eastern Aleppo.

The United Nations Under-Secretary-General For Humanitarian Affairs and Emergency Relief Coordinator Stephen O’Brien said Monday, “Humanitarian conditions in eastern Aleppo have gone from terrible to terrifying and now barely survivable by human beings… Civilians are being isolated, starved, bombed and denied medical attention and humanitarian assistance in order to force them to submit or flee.”