At least 40 people were killed and more than 120 people wounded after twin bomb blasts hit Syria’s capital Damascus on Saturday. Most of the victims were Shia pilgrims, with the attacks targeted at their holy sites in the Bab Musalla area. The bombings are being considered one of the bloodiest ever in the Syrian’s city, Al Jazeera reported.

A number of the pilgrims had been brought by bus to visit the Bab al-Saghir cemetery and a shrine nearby when a bomb went off at the bus station. Several important religious figures are buried at the cemetery and it gets thousands of visitors every year. The second blast took place in the same area 10 minutes later as rescue workers were tending to the wounded.

Interior Minister Mohammed al-Shaar confirmed the toll, but did not suggest who might have been behind the attack. Damascus is considered the stronghold of President Bashar al-Assad, and is relatively safer than other parts of the country where a bloody civil war has been raging for years. Past attacks targeting Shias in Damascus have been carried out by the Islamic State group.