Israeli air strikes in Gaza killed at least 200 people, Palestinian health authorities said, as attacks hit dozens of targets early on Tuesday, ending a weeks-long standoff over extending the ceasefire that halted fighting in January.

The Palestinian militant group Hamas issued a statement accusing Israel of breaching the ceasefire.

Strikes were reported in multiple locations, including northern Gaza, Gaza City and the Deir al-Balah, Khan Younis and Rafah in central and southern Gaza Strip. Palestinian health ministry officials said many of the dead were children.

The Israeli military, which said it hit dozens of targets, said the strikes would continue for as long as necessary and would extend beyond air strikes, raising the prospect that Israeli ground troops could resume fighting.

The attacks were far wider in scale than the regular series of drone strikes the Israeli military has said it has conducted against individuals or small groups of suspected militants and follows weeks of failed efforts to agree an extension to the truce agreed on January 19.

In hospitals strained by 15 months of bombardment, piles of bodies in white plastic sheets smeared with blood could be seen stacked up as casualties were brought in.

The Palestinian Red Crescent said its teams dealt with 86 killed and 134 wounded, but others were brought to overwhelmed hospitals by private cars.

Officials from Nasser Hospital in Khan Yunis, Al-Aqsa Hospital in the central Gaza Strip and Al-Ahly Hospital in Gaza City, which have all been extensively damaged in the war, said that altogether they had received around 85 dead. Authorities also reported separately that 16 members of one family in Rafah, in southern Gaza had been killed.

A spokesperson for the Gaza health ministry said the death toll was at least 200.

Hamas said Israel had overturned the ceasefire agreement, leaving the fate of 59 hostages still held in Gaza uncertain.

Israeli Prime Minister Benjamin Netanyahu’s office accused Hamas of “repeated refusal to release our hostages” and rejecting proposals from U.S. President Donald Trump’s Mideast envoy Steve Witkoff.

“Israel will, from now on, act against Hamas with increasing military strength,” it said in a statement.

In Washington, a White House spokesperson said Israel had consulted the U.S. administration before it carried out the strikes, which the military said targeted mid-level Hamas commanders and leadership officials as well as infrastructure belonging to the militant group.

“Hamas could have released hostages to extend the ceasefire but instead chose refusal and war,” White House spokesperson Brian Hughes said.

In Gaza, witnesses contacted by Reuters said Israeli tanks shelled areas in Rafah in the southern Gaza Strip, forcing many families who had returned to their areas after the ceasefire began to leave their homes and head north to Khan Younis.

Negotiating teams from Israel and Hamas had been in Doha as mediators from Egypt and Qatar sought to bridge the gap between the two sides after the end of an initial phase in the ceasefire, which saw 33 Israeli hostages and five Thais returned by militant groups in Gaza in exchange for some 2,000 Palestinian prisoners.

With the backing of the United States, Israel had been pressing for the return of the remaining 59 hostages still held in Gaza in exchange for a longer-term truce that would have halted fighting until after the Muslim fasting month of Ramadan and the Jewish Passover holiday in April.

However Hamas had been insisting on moving to negotiations for a permanent end to the war and a full withdrawal of Israeli forces from Gaza, in accordance with the terms of the original ceasefire agreement.

“We demand that the mediators hold Netanyahu and the Zionist occupation fully responsible for violating and overturning the agreement,” the group said.

Each side has accused the other of failing to respect the terms of the January ceasefire agreement, and there were multiple hiccups during the course of the first phase. But until now, a full return to the fighting had been avoided.

Israel had blocked deliveries of aid from entering Gaza and had threatened on numerous occasions to resume fighting if Hamas did not agree to return the hostages it still holds.

The army did not provide details about the strikes carried out in the early hours of Tuesday but Palestinian health authorities and witnesses contacted by Reuters reported damage in numerous areas of Gaza, where hundreds of thousands are living in makeshift shelters or damaged buildings.

A building in Gaza City, in the northern end of the strip was hit and at least three houses were hit in Deir Al-Balah in central Gaza. In addition, the strikes hit targets in the southern cities of Khan Younis and Rafah, according to medics and witnesses.

Among those killed was senior Hamas official Mohammad Al-Jmasi, a member of the political office, and members of his family, including his grandchildren who were in his house in Gaza City when it was hit by an airstrike, Hamas sources and relatives said. In all, at least five senior Hamas officials were killed along with members of their families.

Much of Gaza now lies in ruins after 15 months of fighting, which erupted on October 7, 2023 when thousands of Hamas-led gunmen attacked Israeli communities around the Gaza Strip, killing some 1,200 people, according to Israeli tallies, and abducting 251 hostages into Gaza.

The Israeli campaign in response has killed more than 48,000 people, according to Palestinian health authorities, and destroyed much of the housing and infrastructure in the enclave, including the hospital system.