A number of rockets hit a building in the Damascus district of Jaramana early Sunday, reportedly killing Lebanese Hezbollah leader Samir Qantar, according to government loyalists.
Syria's state media blamed "terrorist groups" for the attack, but government loyalists said the explosions were an Israeli strike believed to have killed Qantar, who is reviled in Israel for a 1979 attack that killed four people.
Israel released Qantar in 2008 as part of a prisoner swap with the Lebanese Shi'ite Hezbollah group and he is believed to have rejoined the group since.
The National Defense Forces in Jaramana, which are part of a nation wide grouping of loyalist Syrian militias under the umbrella of the army, mourned Qantar and one of its commanders on its Facebook page.
"His body has been sent to a Damascus hospital moments ago," it said.
After his release, Qantar — a Druze who declared his support for Hezbollah — kept a low public profile. But it is believed that he had become a commander in the National Defense Forces group, which has sent hundreds of its members to fight alongside forces loyal to President Bashar al-Assad.
It was not immediately clear what role Qantar, born in 1962, plays in the fighting in Syria.
Israel has struck Syria several times since the start of the war, mostly destroying weaponry such as missiles that Israeli officials said were destined for Hezbollah, Israel's longtime foe in neighboring Lebanon.
In January, an Israeli strike in Syria killed six members of Hezbollah, including a commander and the son of the group's late military leader Imad Moughniyah in the province of Quneitra, near the Israeli-occupied Golan Heights.
Syrian government loyalists blamed Israel for the attack on Sunday.
"Two Israeli warplanes carried out the raid which targeted the building in Jaramana and struck the designated place with four long range missiles," the NDF in Jaramana Facebook page said.
It was not immediately possible to confirm the reports.
Jaramana is a bastion of government support and is the home of many of Syria's Druze minority as well as Christians.