Lebanon said Israeli air strikes killed more than 55 people on Saturday, many of them in central Beirut.
One strike in the heart of Beirut brought down a residential building and jolted residents across the city.
The strike on the working-class Basta neighbourhood killed at least 20 people and wounded 66, Lebanon's health ministry said.
"We saw two dead people on the ground... The children started crying and their mother cried even more," said Samir, 60, who lives in a building facing the one destroyed.
The attack in the capital was followed by others in the city's southern suburbs after calls by the Israeli military to evacuate.
Hamas says hostage killed in Israeli attack
A woman who was kidnapped and taken to the Gaza Strip has died in an Israeli attack in the enclave's northern, the military arm of Hamas said.
Abu Obaida, spokesman for the al-Qassam Brigades, said on Telegram that another female hostage was critically injured in the attack, attributing the information to the guards who had been holding the women captive.
The Israeli military said it was unable to confirm or deny the claim but that it was in touch with the family of the Israeli hostage that Hamas says was killed.
It also said it was studying footage of the alleged incident released by Hamas.
The Hamas spokesman did not provide any details about the identities of the two hostages.
It was also unclear exactly when the alleged attack took place.
Following Israeli military operations in the past, Hamas has often claimed that hostages had been killed.
Of the approximately 100 hostages still under the control of Hamas and other militant groups in the Gaza Strip, it is estimated that only about half remain alive.
