Officials in Syria said Saturday that the army had found a mass grave on the northeastern edge of Palmyra after the city was recaptured from Islamic State militants.
Authorities said the grave contained at least 40 bodies, including women and three children. Some of the bodies were beheaded, others were reportedly shot.
The London-based Syrian Observatory for Human Rights confirmed the discovery of the mass grave. The monitoring group also said that Islamic State had executed close to 300 people during its nearly 10-month occupation of Palmyra and had buried them on the outskirts of the city.
Syrian government forces backed by heavy Russian air support drove Islamic State out of Palmyra last Sunday.
Syrian army experts detonated hundreds of mines Friday that they say had been planted by Islamic State militants before they fled the town. Officials said the militants had planned to set them off simultaneously as the army moved in.
Palmyra, coined as the "bride of the desert," used to attract tens of thousands of tourists every year.
IS took the city from government forces in a matter of days in May 2015 and later demolished many famous Roman-era monuments in the UNESCO world heritage site. IS deemed the works to be blasphemous because of depictions of the Prophet Muhammad. The destruction has angered and saddened millions around the world who call it another example of Islamic State terrorism.
Also Saturday, heavy fighting was reported between Syrian government forces and rebels, including the al-Qaida-affiliated al-Nusra Front, outside Aleppo.
The Syrian Observatory said the militants had taken control of a strategically important hill south of the city. At least 16 opposition fighters were killed, along with a number of Syrian soldiers.
The al-Nusra Front is not part of the month-old cease-fire in Syria. But some of the militant fighters have slipped in among rebel groups that have signed the truce, attracting Syrian military gunfire and putting the cease-fire at risk.
In pictures: The Ancient City of Palmyra, Syria