Israeli strikes overnight in Gaza have killed at least 81 people, including many children, local hospital officials said.
It is likely to be the most serious challenge to the tenuous ceasefire in Gaza since it came into force earlier this month.
The Israeli military said on Wednesday that the ceasefire was back in effect after it completed a number of strikes in which “terror targets and terrorists” were hit inside Gaza.
Officials said in a statement that troops struck “30 terrorists holding command positions within terrorist organisations” operating inside the Palestinian territory.
The military said Israeli forces will continue to uphold the ceasefire agreement but would respond “firmly” to any violation.
The deadliest ceasefire breach to date came after Israeli Prime Minister Benjamin Netanyahu ordered the military to conduct “powerful strikes” on Gaza, accusing Hamas of violating the fragile ceasefire.
Hamas said in response that that it would delay handing over the body of another hostage.
US President Donald Trump defended the strikes, saying Israel was justified in carrying them out after what he said was an incident in which Hamas killed an Israeli soldier during an exchange of gunfire in Rafah, the southernmost city in Gaza.
Hamas denied any involvement in that shooting and accused Israel of violating the ceasefire deal.
Shifa Hospital director Mohammed Abu Selmia said the hospital received 21 bodies killed in the strikes, including seven women and six children.
He said he expects the death toll to rise as many of the 45 wounded received by the Gaza City hospital are in critical condition, including 20 children.
The Aqsa Hospital in Gaza’s central city of Deir al-Balah said at least 10 bodies, including three women and six children, arrived overnight after two Israeli air strikes there.
In southern Gaza, the Nasser Hospital in Khan Younis said it received 20 bodies after five Israeli strikes in the area, of whom 13 were children and two were women.
In central Gaza, the Al-Awda Hospital said it received 30 bodies, including 14 children.
Mr Netanyahu’s order to launch strikes came after an Israeli official said its forces were fired on in southern Gaza and after Hamas handed over body parts on Monday that Israel said were the partial remains of a hostage recovered earlier in the war.
The prime minister called the return of the body parts a “clear violation” of the ceasefire agreement, which requires Hamas to return the remaining hostages in Gaza as soon as possible.
Israeli officials also accused Hamas of staging the discovery of the remains on Monday, sharing a 14-minute edited video captured by a military drone in Gaza.
Israel notified the US before launching the strikes on Tuesday, according to two US sources.
Mr Trump told journalists on Wednesday that Israel “should hit back” when its troops come under attack.
But he said he is still confident the ceasefire will withstand the escalation in violence because “Hamas is a very small part of the overall Middle East peace. And they have to behave”. If not, they will be “terminated”, he added.
An Israeli military official said on Wednesday that the soldier was killed on Tuesday afternoon by “enemy fire” targeting his vehicle in Rafah.
The official said troops in the area came under attack numerous times on Tuesday as they worked to destroy tunnels and Hamas infrastructure. Israel identified the soldier who was killed as Master Sergeant Yona Efraim Feldbaum, 37.
Hamas insisted it was not involved in the Rafah gunfire and reiterated its commitment to the ceasefire.
“The violent strikes carried out by Israel across the strip is a blatant violation of the ceasefire deal,” said the militant group, calling on mediators to pressure Israel to stop.
Subscribe or register today to discover more from DonegalLive.ie
Buy the e-paper of the Donegal Democrat, Donegal People's Press, Donegal Post and Inish Times here for instant access to Donegal's premier news titles.
Keep up with the latest news from Donegal with our daily newsletter featuring the most important stories of the day delivered to your inbox every evening at 5pm.