An Israeli strike killed a commander of Hezbollah's elite Radwan force in south Lebanon on Monday, according to security sources familiar with the group's operations in the country.
It's one of the most high-profile attacks on its senior officers in three months of hostilities with Israel.
Wissam Al Tawil, the deputy head of a Radwan unit, and another Hezbollah fighter were reportedly killed when the car they were in was struck in the village of Majdal Selm, some 6 km from the border.
One of the security sources called Tawil's death "a very painful strike". Another said, "things will flare up now."
Hezbollah says its campaign aims to support Palestinians in the Gaza Strip. The hostilities between the group and Israel have largely been contained to areas near the border.
Tensions spiked higher last week when an Israeli strike killed deputy Hamas chief Saleh al-Arouri in Beirut's southern suburbs, an area controlled by Hezbollah. Israel has neither confirmed nor denied its responsibility for that attack.
Hezbollah on Saturday said it had hit a key Israeli observation post with 62 rockets as a "preliminary response" to Arouri's killing.
US military says it turned away blockade runner trying to reach Iranian port
Jubilant PSG supporters spill onto Paris streets, some clash with police
WHO chief urges safe burials in visit to heart of Ebola outbreak
Rescuers pull four from flooded cave in Laos
