In what came as the heaviest assault in Gaza since a ceasefire took effect in January, Israel launched several airstrikes across the Gaza Strip on early Tuesday, claiming to have hit dozens of Hamas targets.
According to Palestinian health officials, the number of casualties has gone up to 413, including women and children.
Prime Minister Benjamin Netanyahu said he ordered the strikes because of a lack of progress in talks to extend the ceasefire. The White House said it had been consulted and voiced support for Israel's actions.
“Israel will, from now on, act against Hamas with increasing military strength,” Netanyahu's office said.
The surprise attack shattered a period of relative calm during the Muslim holy month of Ramadan and raised the prospect of a full return to fighting in a 17-month war that has killed tens of thousands of Palestinians and caused widespread destruction across Gaza.
It also raised questions about the fate of the roughly two dozen Israeli hostages held by Hamas who are believed to still be alive. Hamas accused Netanyahu of upending the ceasefire agreement and exposing the hostages ”to an unknown fate”.
In a statement, it called on mediators to hold Israel “fully responsible for violating and overturning the agreement”.
The strikes came as Netanayahu comes under mounting domestic pressure, with mass protests planned over his handling of the hostage crisis and his decision to fire the head of Israel's internal security agency.
An Israeli airstrike flattened a prison run by the Hamas-led government in Gaza Strip, killing dozens of prisoners and policemen, according to hospital records.
The prison was located in the urban Shati refugee camp in Gaza City.
Associated Press footage showed a collapsed building and people trying to reach bodies buried under the rubble.
The bodies of more than three dozen prisoners and guards were taken to the nearby Shifa hospital.
(With inputs from AP)