The death toll from five days of ferocious fighting beween Hamas and Israel rose sharply overnight as Israel kept up its bombardment of Gaza Wednesday after recovering the dead from the last communities near the border where Palestinian militants had been holed up.

In Israel, the death toll from Saturday’s shock cross-border assault by Hamas militants rose to 1,200, making it the deadliest attack in the country’s 75-year history, while Gaza officials reported more than 900 people killed as Israel pounded the territory with air strikes.

Hamas said two of its top officials had been killed, while Israel’s military said the bodies of roughly 1,500 Hamas infiltrators had been found.

Prime Minister Benjamin Netanyahu has warned Israel’s military response to Saturday’s attack is only the start of a sustained war to destroy the Islamist group and “change the Middle East”.

Fears of a regional conflagration have surged ahead of an expected Israeli ground incursion into Gaza.

How the Hamas attack on Israel unfolded

Iran’s Khamenei denies involvement in Hamas attack on Israel

At least 30 people were killed and hundreds wounded as Israel pounded the Gaza Strip with hundreds of air strikes overnight, a Hamas government official said Wednesday. The strikes destroyed several buildings of the Hamas-linked Islamic University in Gaza City, a university official said.

The Israeli military confirmed it had hit dozens of Hamas targets during the night. It said fighter jets destroyed “advanced detection systems” that Hamas used to spot military aircraft.

They also hit 80 Hamas targets in the Beit Hanoun area of the northeastern Gaza Strip, including two bank branches used by the Islamist group to “fund terrorism” in the enclave, the military said.

In response to Saturday’s attack, Israel imposed a “total siege” on Gaza, suspending supplies of food, water, electricity, and fuel to the already blockaded enclave. Hamas, which has controlled the Gaza Strip since 2007, is threatening to execute hostages kidnapped in Israel, including young people captured during a music festival where around 270 died.

Discovering bodies

Israel has been left reeling by Hamas’s unprecedented ground, air and sea assault, likening it to the September 11, 2001 attacks on the United States.

In announcing Israel’s latest death toll on Wednesday morning, army spokesperson Lieutenant Colonel Jonathan Conricus said the figure was rising not because of the ongoing fighting, but because “we are discovering bodies of dead Israelis in the various communities that Hamas infiltrated and where they conducted their massacres”.

During Saturday’s attack, Hamas gunmen killed more than 100 people in the kibbutz of Beeri alone, said Moti Bukjin, a volunteer with the charity Zaka.

US President Joe Biden condemned the Hamas attacks as “sheer evil”, and Netanyahu said the militants committed “savagery never seen since the Holocaust”, including the beheading of soldiers.