File photo shows Free Syrian Army fighters clean their weapons and check ammunition at their base on the outskirts of Aleppo, Syria.

Zahran Aloush, head of the powerful Jaysh al-Islam Syrian rebel group, was killed on Friday east of Damascus, a monitoring group and Syria’s opposition said.

The Syrian Observatory for Human Rights monitor said Aloush and five other commanders were killed “in an air strike that targeted one of their meetings in Eastern Ghouta.”

Aloush’s death was confirmed on Twitter by the head of Syria’s opposition National Coalition.

It was not immediately clear who had carried out the air strike.

However, Reuters reported that Aloush was killed in the aerial raid that targeted his group’s headquarters, citing two rebel sources as saying on Friday. They said a secret headquarters of the rebel group, which is the largest rebel faction in the area and has thousands of fighters, was targeted by what they described as Russian planes.

Activists also said the air strike killed Aloush’s deputy and his spokesman in southern Damascus, Al Arabiya News Channel reported.

Jaysh al Islam, with thousands of trained fighters, is the biggest and seen as the most organized rebel group. It has been effectively running the administration of Eastern Ghouta.

Before setting up Jaysh al Islam, Aloush had founded Liwa al-Islam, or the Brigade of Islam, with his father Abdallah, a Salafist Syrian cleric based in Saudi Arabia.

Aloush was ideologically at odds with ISIS and al-Qaeda, espousing a more moderate brand of Islam.

The news of the air strike comes after some 4,000 people, half of them militant fighters, decided to leave three besieged districts south of Syria’s capital at the weekend as part of a landmark ceasefire.

ISIS militants and its rival, Al-Qaeda’s Syrian affiliate Al-Nusra Front, will reportedly quit the districts of Qadam, Hajar al-Aswad and the besieged Palestinian camp of Yarmuk.

Zahran Aloush

Related articles across the web

• Russian Airstrikes Kill 39 Civilians in Northern Syria
• Islamic State or Wahhabi Colony?
• Who are the Syrian rebels holding talks in Saudi Arabia?
• Syria army retakes key hilltop in coastal province
• FPI Bulletin: Russian Support Halts Rebel Gains in Syria
• Israel Supports Islamic Terrorists
• The Syrian Civil War: Great News Out Of Syria - Syrian Army Holds Victory Parade In Homs After "Al Qaeda" Stronghold Is Cleared!
• Syrian troops seize air base in rebel-held suburb
• Dropping Russian Bombs on Syria...12-15-15 Mouse Report
• Syrian infighting poses challenge for Turkey, US