This file photo released on Sunday, May 17, 2015, by the Syrian official news agency SANA, shows the general view of the ancient Roman city of Palmyra, northeast of Damascus, Syria.

The Islamic State of Iraq and Syria (ISIS) militant group executed three people in Syria’s ancient city of Palmyra by binding them to three historic columns and blowing them up, a monitoring group said Monday.

The UK-based Syrian Observatory for Human Rights said ISIS on Sunday “tied three individuals it had arrested from Palmyra and its outskirts to the columns… and executed them by blowing up” three columns.

Since taking the city in May, ISIS have already destroyed many of its statues and two of its temples. In July, ISIS released a video showing a mass execution taking place in Palmyra’s ancient amphitheater.