The Israeli military said Friday it carried out an airstrike on the central headquarters of Hezbollah in Beirut, where a massive explosion levelled buildings in a southern district, sending clouds of orange and black smoke billowing in the skies.

The strike in the Beirut suburb of Dahiyeh came shortly after Israeli Prime Minister Benjamin Netanyahu addressed the UN, vowing that Israel's campaign against Hezbollah would continue. Not long before the explosion, thousands were massed in the suburb for the funeral of three Hezbollah members, including a senior commander, killed in earlier strikes.

There was no immediate word on casualties in the strike.

The Israeli army spokesperson, Rear Adm. Daniel Hagari, said it targeted the main Hezbollah headquarters, located beneath residential buildings. Hezbollah's Al-Manar TV said four buildings were reduced to rubble in the blast, so powerful it rattled windows and shook houses some 30 kilometres north of Beirut. Ambulances were seen headed to the scene of the explosions, sirens wailing.

Earlier in the day, an Israeli airstrike killed a family of nine in a Lebanese border village, authorities said, as Lebanon struggled to deal with a rising death toll, a wave of tens of thousands fleeing their homes and the possibility of an all-out war between Israel and Hezbollah.

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CBC News senior international correspondent Margaret Evans says the streets of Beirut are quiet for a city its size. Many people are trying to escape Israeli airstrikes in Lebanon's south, moving farther north in the country, into Syria or overseas.