It was the largest number of Israeli civilian fatalities since 16 July, when eight workers were killed as a rocket struck a train depot in Haifa.
And although last night Sheikh Hassan Nasrallah, the Hezbollah leader, offered for the first time since the recent hostilities began to stop the attacks if Israel ended its air strikes in Lebanon, both sides also threatened to escalate war.
Sheikh Nasrallah went on to say that Hezbollah would target Tel Aviv if Israel attacked central Beirut.
In response, sources told Israeli TV Israel would destroy Lebanon's infrastructure if that threat was carried out.
Then late last night, two huge explosions rocked Beirut in what local media said were new Israeli air strikes on Hezbollah strongholds south of the city. There were no immediate reports of casualties.
Four Israeli soldiers were also killed in southern Lebanon yesterday, taking the Israeli death toll to 68 - 27 of them civilians.
Fouad Siniora, the Lebanese prime minister, said the war had killed 900 people in his country and wounded 3,000, with a third of the casualties children under 12. He also said a million Lebanese, a quarter of the population, had been displaced and the country's infrastructure devastated.
Ehud Olmert, the Israeli prime minister, who launched the offensive after Hezbollah kidnapped two soldiers in a cross-border raid, claimed on Wednesday that Israel had destroyed the militant group's infrastructure.
But in a co-ordinated barrage starting at 4pm yesterday local time, Hezbollah struck all across northern Israel, hitting the port of Acre, the mixed Arab-Jewish town of Maalot-Tarshiha, Tiberias, Carmiel, Kiryat Shmona and other centres in its most intensive bombardment of the war.
Among those killed were a father and daughter in Acre.
Ofer Pines-Paz, an Israeli cabinet minister, called on citizens to stay in shelters and secure rooms. "This is not over," he warned.
Meanwhile, three Israeli soldiers, part of the 10,000-strong force carving out a five-mile wide security zone in southern Lebanon, died when their armoured vehicle suffered a direct hit from a Hezbollah anti-tank missile, the army said.
State-run Israel Radio said that troops killed 14 Hezbollah guerrillas yesterday and captured six. Other reports said it was not clear whether the six belonged to Hezbollah or not.
Mr Olmert said in interviews that the fighting would take several days "and not weeks" until the international community decided on the deployment of an international force in southern Lebanon. But Hezbollah, its confidence growing, insisted it would not agree to a ceasefire as long as a single Israeli soldier remained on Lebanese soil.