At least 42 people were killed and more than 84 wounded in a suicide bomber attack Thursday inside a mosque in the capital of Damascus, Syrian TV reports.
Top Sunni Muslim preacher and longtime Assad supporter Sheikh Mohammad Said Ramadan al-Buti was reportedly killed in the blast. Al-Buti's grandson was also reportedly killed.
The explosion hit as the mosque was packed with worshippers for Friday evening prayers.
The blast occurred in the Eman Mosque in the central Mazraa district, according to Reuters.
Residents in the area said they believed the explosion may have been caused by a mortar bomb, Reuters reports.
TV footage showed wounded people and bodies with severed limbs on the blood-stained floor of the mosque.
Sirens echoed in the capital as ambulances rushed to the scene of the explosion, which was sealed off by the military.
Al-Buti's death is a big blow to Syria's embattled leader, who is fighting mainly Sunni rebels seeking his ouster. Al-Buti has been a vocal supporter of his regime since the early days of his father and predecessor, the late President Hafez Assad.
In recent months, Syrian TV has carried his sermon from mosques in Damascus live every week. He also has a regular religious TV program.
Al-Buti's death removes one of the few remaining pillars of support of the Alawite leader among the majority sect that has risen up against him.
The Associated Press contributed to this report.