Residents of the Iranian-backed group's stronghold in southern Beirut reported one large explosion that shook the area early Sunday, triggering a fire. They said the nature of the blast in the Moawwad neighborhood was not immediately clear, but said it may have been caused by an Israeli drone that went down in the area amid Israeli air activity in neighboring Syria.
They said they heard an aircraft flying just before the blast and reported later that the Iranian-backed Hezbollah group sealed off the area. The blast occurred near the militant group's media office in the Moawwad district.
The Hezbollah official spoke to The Associated Press on condition of anonymity as the person was not authorized to speak on the record to journalists. No details were immediately available. Journalists on the scene were not allowed to film or take pictures. One building appeared to be slightly damaged where the drone went down. A man was seen taking away metal parts in a white plastic bag that he said contained parts of the aircraft that went down.
The Israeli military said it does not comment on "foreign reports."
Israeli warplanes regularly violate Lebanese airspace and have struck inside neighboring Syria from Lebanon on numerous occasions.
A few hours earlier, late Saturday, the Israeli military attacked targets near Syria's capital of Damascus in what it said was a successful effort to thwart an imminent Iranian drone strike on Israel, stepping up an already heightened campaign against Iranian military activity in the region.
The late-night airstrike, which triggered Syrian anti-aircraft fire, appeared to be one of the most intense attacks by Israeli forces in several years of hits on Iranian targets in Syria.
Lt. Col. Jonathan Conricus, a military spokesman, said Iran's Revolutionary Guards' Al Quds force, working with allied Shiite militias, had been planning to send a number of explosives-laden attack drones into Israel.
On Twitter, Israeli Prime Minister Benjamin Netanyahu called the attack by Israeli warplanes a "major operational effort."
Syrian state TV said the country's air defenses had responded to "hostile" targets over Damascus and shot down incoming missiles before they reached their targets.
In recent days, U.S. officials have said that Israeli strikes have also hit Iranian targets in Iraq.
Hezbollah and Israel fought a monthlong war in 2006. The volatile border between the two countries, which remain technically in a state of war, has been mostly calm since.