A senior Hezbollah commander has been killed in an Israeli airstrike in southern Lebanon, according to a Lebanese security official.
Sky News has been unable to independently verify the claims, and Israel is yet to respond to them.
Security sources told the Reuters news agency the victim was the deputy head of a unit within Hezbollah's elite Radwan force.
They identified him as Wissam al Tawil and said he was killed along with another fighter.
Sources told the agency the fatalities came when a car was hit in a strike on the Lebanese village of Majdal Selm.
Middle East correspondent for Sky News, Alistair Bunkall, said the commander belonged to the Radwan force - and the strike comes as US secretary of state Antony Blinken is heading to Israel for talks.
He said: "So clearly the Israelis are deliberately trying to send a message to Hezbollah, by targeting this commander from this unit, that they are in no mood to be messed around on the border.
Image: Hezbollah commander Wissam al Tawil. Pic: Hezbollah Military Media/AP
"Whether or not Hezbollah listen to that and decide to back off - or the opposite could happen and things could flare up.
"At the moment, with tensions as they are, it's more likely things will flare up."
Mr Blinken is back in the region as part of efforts to stop the conflict from spreading.
A source in Lebanon familiar with the matter told Reuters Tawil was one of the most senior Hezbollah commanders killed in the hostilities so far.
Among the photographs of Tawil circulated by the group is one showing him sitting next to the former leader of the Iranian Quds Force, Qassem Soleimani, who was killed in Baghdad four years ago by a US drone strike.
Image: Hezbollah commander Wissam al Tawil, left and Qassem Soleimani. Pic: Hezbollah Military Media/AP
Another image shows him with Mustafa Badreddine, a former senior military leader of Hezbollah, who died in an explosion in 2016.
Tawil's death is "a very painful strike", a security source said.
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Image: Hezbollah commander Wissam al Tawil (right) and Mustafa Badreddine. Pic:Hezbollah Military Media/AP
The US, which has provided crucial military and diplomatic support for the offensive, has called on Israel to take greater measures to spare civilians.
However, it has also joined it in rejecting international calls for a ceasefire.
Tens of thousands of people have sought shelter in Gaza's hospitals, which are also struggling to treat dozens of people wounded each day in Israeli strikes.
Only 13 of Gaza's 36 hospitals are even partially functioning, according to the UN humanitarian office.