The leader of al-Qaeda-linked Ahrar al-Sham terrorist group has been killed in a bomb attack that targeted the Takfiri militant’s headquarters in the northwestern Syrian province of Idlib.

Majed Hussein al-Sadeq, along with three other members of the militant outfit, were killed on Saturday when the attack targeted Ahrar al-Sham headquarters in the town of Binnish, located about 10 kilometers (6.2 miles) northeast of Idlib, the so-called Syrian Observatory for Human Rights reported.

The Britain-based group noted that an unknown person parked his motorcycle near the terrorist base, and headed on foot towards a gathering of the Takfiris. He then detonated his explosives-laden belt, killing Sadeq and three of his comrades.

An unspecified number of the extremists was also injured in the incident. The Observatory reported that the death toll is expected to rise as some of the wounded militants are in critical condition.

Last July, one of Ahrar al-Sham's most senior leaders, identified as Abu Abdel Rahman Salqin, was killed after two unidentified bombers detonated their explosives at the terrorist group’s bases in the Abu Talha area of Idlib.

Six other high ranking members of the terrorist group were also killed in the deadly incident.

Ahrar al-Sham, one of the oldest and largest terrorist groups operating in Syria since 2011, is mostly active in the country's northwestern part. The group is allied with al-Nusra Front, an offshoot of al-Qaeda terror network in Syria.

According to a February report by the Syrian Center for Policy Research, the conflict has claimed the lives of over 470,000 people, injured 1.9 million others, and displaced nearly half of the pre-war population of about 23 million within or beyond Syria’s borders. The observatory, however, puts the number at about 270,000.