JERUSALEM/BEIRUT -- Israel's army announced on Tuesday that it killed Hezbollah's top military commander, Fouad Shokor, in an airstrike in Beirut, saying the assassination was a retaliation for a cross-border rocket that killed 12 youngsters on Saturday.

Hezbollah, a Lebanese militant group and political party, did not immediately confirm his condition. Earlier Lebanese media reports said the attack targeting Shokor was missed.

"Tonight, IDF (Israel Defense Forces) conducted a targeted strike in Beirut, eliminating Fouad Shokor, also known as 'Sayyid Muhsan,' the most senior military commander and head of the Strategic Unit of Hezbollah," IDF's Spokesperson Daniel Hagari told a press briefing in Tel Aviv.

Hagari said that Shokor served also as Hezbollah Secretary-General Hassan Nasrallah's "right-hand man" and was Nasrallah's adviser for planning and directing wartime operations.

In a press release, IDF blamed Shokor for being responsible for the deadly rocket on Saturday that hit a football pitch in Majdal Shams, a Druze town in the Israeli-occupied Golan Heights.

The commander "was responsible for the majority of Hezbollah's most advanced weaponry, including precise-guided missiles, cruise missiles, anti-ship missiles, long-range rockets, and UAVs. He was responsible for force build-up, planning, and execution of terror attacks against the State of Israel," IDF said.

A strong blast was heard in the Lebanese capital on Tuesday night, and video footage on social media showed mass destruction of a residential building, with rubble scattered in the street.

Lebanon's Al Manar TV cited the Lebanese health ministry as reporting 74 people injured along with three killed in the attack around Hezbollah's Shura Council.

Lebanese Prime Minister Najib Mikati condemned the attack, saying Lebanon preserves its right to take all necessary measures that contribute to deterring the aggression.

Lebanese Foreign Affairs Minister Abdallah Bou Habib said Lebanon will submit a complaint to the UN Security Council over the attack.