Two paramedics were killed in an Israeli strike on a medical centre in the southern Lebanese town of Blida on Thursday night.
The paramedics worked for the Islamic Health Association, a Hezbollah-affiliated health service.
Hezbollah also announced the death of one of its fighters from Blida on Thursday, but it did not specify whether he died in the same strike as the paramedics.
The strike completely destroyed the medical centre and several ambulances.
Thursday's strike was at least the fourth Israeli airstrike on medical infrastructure since cross-border clashes started between Hezbollah and Israel in the wake of Hamas's 7 October surprise attack.
Lebanon's Ministry of Health issued a statement condemning the Israeli attack on the Blida medical centre, which it said was "in violation of international laws and norms."
"The Ministry stresses the need to keep health centres and health workers who carry out medical and humanitarian work neutral, and they cannot be obstructed or be targeted," the Health Ministry said on Friday.
Mourners reportedly came under machine gun fire from the Israeli army as they attempted to dig graves for the two paramedics.
The attack on the medical centre came as fighting between Hezbollah intensified in recent weeks, with Israeli strikes reaching far deeper than before.
In the last two weeks, Israel has killed 12 civilians in south Lebanon, including four children.
Head of Hezbollah Hassan Nasrallah vowed that Israel would "pay in blood" for its attacks on civilians.
On Thursday night, Hezbollah let off a salvo of rockets targeting Israeli army barracks in the Golan Heights, which the group said was in retaliation for the strikes on Blida.
On Friday, Israeli strikes completely destroyed a home in the border town of Kafr Kila, with no injuries being reported.
Western and Arab diplomats have raced to prevent an all-out war between Israel and Hezbollah but have not managed to slow the pace of clashes.
Israel has said it wants a complete withdrawal of Hezbollah forces beyond the Litani River – about 30 kilometres from the border.
Hezbollah said it will not engage in any negotiations around its presence in the south or the border without a ceasefire in Gaza.
On Friday, Israel carried out a naval training exercise simulating large-scale combat on its northern front with Lebanon.