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.
At least eight Palestinians, most of them children, were killed and more than a dozen others were wounded in central Gaza on Sunday, local officials said, in an Israeli missile strike which the military said missed its intended target.
North Korean leader Kim Jong Un told Russia's top diplomat his country was ready to "unconditionally support" Moscow's every effort to resolve the conflict in Ukraine, state media reported on Sunday, as the two countries held high-level strategic talks.
A preliminary report depicted confusion in the cockpit shortly before an Air India jetliner crashed, killing 260 people last month, after the plane's engine fuel cutoff switches almost simultaneously flipped, starving the engines of fuel.
US President Donald Trump defended the state and federal response to deadly flash flooding in Texas on Friday as he visited the stricken Hill Country region, where at least 120 people, including dozens of children, perished a week ago.
Russia pounded Ukraine with hundreds of drones and dozens of missiles on Saturday, in the fourth major attack this month, targeting western cities and killing at least two people in Chernivtsi on the border with Romania.
Dubai Police have arrested and extradited three Belgians wanted by International Criminal Police Organisation (INTERPOL) for cross-border organised crime.
UAE President His Highness Sheikh Mohamed bin Zayed Al Nahyan has emphasised the importance of dialogue and diplomacy in resolving regional crises during a call with his Turkish counterpart Recep Tayyip Erdoğan.