An Israeli air strike targeted a senior Hezbollah commander in Beirut's southern suburbs late on Tuesday.
The Israeli military said it was in retaliation for a cross-border rocket attack three days before that killed 12 children and teenagers.
A loud blast was heard and a plume of smoke could be seen rising above the southern suburbs - a stronghold of the armed group Hezbollah - at around 7:40 pm (1640 GMT), a Reuters witness said.
A senior Lebanese security source said a senior Hezbollah commander had been the target of the air strike and his fate remained unclear.
Lebanon's state-run national news agency said an Israeli air strike had targeted the area around Hezbollah's Shura Council in the Haret Hreik neighbourhood of the capital.
Beirut has been on edge for days ahead of an anticipated Israeli attack in reprisal for the rocket strike on the Israeli-occupied Golan Heights on Saturday that killed the 12 youngsters in a football field in a Druze village.
Hezbollah has denied involvement in that attack.
As diplomats sought to contain the fallout, US Defence Secretary Lloyd Austin said he did not believe a fight was inevitable between Hezbollah and Israel, though he remained concerned about the potential for escalation.
Indonesian authorities will continue searching on Monday for more than a hundred people still missing after a passenger ship sank in the Java Sea last week, with the confirmed death toll now at 10, its rescue agency said on Sunday.
Police have arrested Aleema Khan, the sister of Pakistan's jailed ex-prime minister Imran Khan, at her house in Lahore, a spokesperson from Khan's Pakistan Tehreek-e-Insaf party said on Sunday.
US President Donald Trump said on Sunday the triumphal arch he plans to build near Arlington National Cemetery in Washington would double as a "military complex" housing drones and snipers, as well as storing large quantities of ammunition.
Violence flared in the occupied West Bank on Sunday when a suspected Palestinian gunman shot dead an Israeli man, police said, and Israeli soldiers killed a Palestinian motorist who the military said was attempting to run them over.
The largest Ukrainian drone attack reported so far on the Moscow region killed three people and damaged part of an oil refinery in the capital, authorities said on Sunday, as Russia votes in the final day of parliamentary elections.