On Friday (April 1), nearly a week after capturing Palmyra from Islamic State militants, Syrian troops discovered a mass grave of about 45 bodies on the north-eastern edge of the city. The Syrian military  “uncovered a mass grave of officers, soldiers, members of the popular committees (pro-regime militia) and their relatives,” a source told the L’Agence France-Presse (AFP). Of those 45 bodies, 24 were civilians, including women and children.

“They were executed either by beheading or by shooting,” the source said. Some of the deceased were even tortured before death.

IS militants were in Palmyra since May of 2015, for nearly 10 months. In their first four days of control, the Syrian state media reported that the IS militants killed at least 400 people.

The Syrian troops, backed by Russian air strikes, launched a major offensive attack to retake Palmyra. In this attack, the Syrian Observatory for Human Rights reported that 400 IS militants and 188 Syrian troops were killed.

“That’s the heaviest loss that IS has sustained in a single battle since its creation ,” says Rami Abdel Rahman, the director of the Observatory.

In this battle, however, the ancient city suffered significant damage to many of the structures including the 1,800-year-old Arch of Triumph and the nearly 2,000-year-old Temple of Baalshamin. IS militants also beheaded 82-year-old antique expert, Khaled al-Asaad, who refused to lead them to hidden Palmyra antiques.

Many buildings are in pieces, but the Syrian antiquities chief, Maamoun Abdulkarim, said the priceless artifacts had survived better than they expected.

“We were expecting the worst. But the landscape, in general, is in good shape,” he says. “We could have completely lost Palmyra. The joy I feel is indescribable.”

Palmyra, located in the Homs countryside northeast of Damascus, the Syrian capital, was a caravan oasis when Romans overtook it in the mid-first century. In the centuries that followed, the area “stood at the crossroads of several civilizations” with its art and architecture mixing Greek, Roman and Persian influences, according to UNESCO, the U.N. agency that documents the world’s most important cultural and natural sites. Palmyra is a place of ancient ruins that is considered among the world’s most treasured, and is recognized by the United Nations as a World Heritage site.

The neighbouring town, where more than 70,000 people lived before the war, is completely deserted as the remaining residents fled a month ago when the Syrian military began its offensive strategy to take back the city.

Although Syrian President Bashar al-Assad calls the retaking of Palmyra an “important” victory, many people have died in the process. The war against ISIS has torn the country apart killing more than 250,000 people, injuring around one million and displacing millions more.