BEIRUT: A suicide bombing tore through a mosque in the Syrian capital Thursday, killing a top Sunni Muslim imam and longtime supporter of President Bashar Assad along with at least 41 other people. The assassination of Sheikh Mohammad Said Ramadan al-Buti removes one of the few remaining pillars of support for the Alawite leader among the majority sect that has risen up against him.

The powerful explosion struck as Buti, an 84-year-old imam and religious scholar who appeared often on TV, was giving a religious lesson in the Iman Mosque in the central Mazraa district of Damascus, according to state TV.

Suicide bombings blamed on extremists fighting with the rebels have become common in Syria’s civil war. But Thursday’s explosion marked the first time a suicide bomber detonated his explosives inside a mosque.

Syrian TV footage showed wounded people and bodies with severed limbs on the blood-stained floor and later, bodies covered in white body bags lined up in rows. Sirens wailed through the capital as ambulances rushed to the scene of the explosion, which was sealed off by the military.

Among those killed were Buti’s grandson, the TV said, adding that at least 84 were wounded.

The government warned that those fighting to topple the regime would face retribution for the attack, saying that the “cowardly act that targeted the scholar Buti will not go unpunished,” according to the state news agency SANA.

Buti’s death was a big blow to Syria’s embattled leader, who is fighting mainly Sunni rebels seeking his ouster.

The imam has been a vocal supporter of his regime since the early days of Assad’s father and predecessor, the late President Hafez Assad. He was the regular imam of the eighth century Umayyad Mosque, but Syrian TV said he was giving a religious sermon to students at Iman Mosque when the explosion occurred.

In recent months, Syrian TV has carried his sermon from mosques in Damascus live every week.

Syrian TV began its evening newscast with a phone announcement from Religious Endowments Minister Mohammad Abdel-Sattar al-Sayyed declaring Buti’s “martyrdom” as his voice choked up. It then showed parts of his sermon last Friday in which he praised the military for battling the “mercenaries” and said Syria was being subjected to a “universal conspiracy.”

Rebel spokesman Loay Mekdad said units associated with the opposition’s Free Syrian Army were not behind the attack.

“We, in the Free Syrian Army do not take any responsibility for this operation. We do not do these types of suicide bombings and we do not target mosques,” he told Al-Arabiya television.

Some opposition activists argued the rebels could not have been behind the attack and called it a government plot.

“The regime eliminated Buti,” said Leena al-Shami, a Damascus activist speaking on Skype.

“I don’t think Buti could have done more, his role was over. Now the regime wanted to make a martyr of him.”

The rebels also captured a village and other territory on the edge of the Golan Heights as fighting closed in on the strategic plateau that Israel captured from Syria in 1967, activists and officials said.

The battles near the town of Qunaitra in southwest Syria sent many residents fleeing, including dozens who crossed into neighboring Lebanon. The fighting in the sensitive area began Wednesday near the cease-fire line between Syrian and Israeli troops.

One of the worst-case scenarios for Syria’s civil war is that it could draw in neighboring countries such as Israel or Lebanon.

There have already been clashes with Turkey, Syria’s neighbor to the north. And Israel recently bombed targets inside Syria said to include a weapons convoy headed for Hezbollah in Lebanon.

If the rebels take over the Qunaitra region, it may bring radical Islamist militants to a front line with Israeli troops. Syrian rebels are made of dozens of groups including the powerful, Al-Qaeda-linked Nusra Front, which the Obama administration labels a terrorist organization.

Israel has said its policy is not to get involved in the Syrian civil war, but it has retaliated for sporadic Syrian fire that spilled over into Israeli communities on the Golan Heights.

The Britain-based activist group Syrian Observatory for Human Rights said rebels seized control of parts of villages a few kilometers from the cease-fire line with Israel after fierce fighting with regime forces.

The Local Coordination Committees, another anti-regime activist group, reported heavy fighting in the nearby village of Sahm al-Golan and said rebels are attacking an army post.

Rami Abdel-Rahman, who heads the Observatory, said the fighting around the town of Arnabeh intensified, a day after rebels captured it. He added that the rebels captured two nearby army posts.

In Lebanon, security officials said 150 people, mostly women and children, walked for six hours in rugged mountains covered with snow to reach safety in the Lebanese border town of Shebaa.

The officials, who did not want to be identified because they were not authorized to speak to the media, said the Syrians fled from the town of Beit Jan, near the Golan Heights.