At least 65 people were found dead on Tuesday with gunshot wounds to the head and bound hands in a district in the Syrian city of Aleppo, Reuters reported. A U.K.-based Syrian human rights organization said the death toll could be as high as 80 in what it called a "new massacre." Government forces and rebels in Syria have both been accused by human rights groups of carrying out summary executions in the 22-month-old conflict, which has claimed more than 60,000 lives. Photos posted by online activists showed muddied bodies of about a dozen men lying by a small river in what they said was the Bustan al-Qasr neighborhood of Aleppo. It was not clear who carried out the killings. Rebels occupied Aleppo over the summer but have been stuck in a stalemate with government forces. The city is divided in half between the two sides.