JERUSALEM/CAIRO. Israel on Tuesday launched a large-scale ground assault on Gaza City, declaring “Gaza is burning” as Palestinians described the most intense bombardment since the start of the war two years ago.

An Israel Defense Forces (IDF) official confirmed that troops were advancing deeper into the enclave’s main city and that reinforcements would arrive in the coming days to confront an estimated 3,000 Hamas combatants still present.

“Gaza is burning,” Defense Minister Israel Katz posted on X. “The IDF strikes with an iron fist at the terrorist infrastructure and IDF soldiers are fighting bravely to create the conditions for the release of the hostages and the defeat of Hamas.”

The move came despite warnings from European leaders threatening sanctions and concerns voiced by some Israeli commanders that the operation could prove costly. Washington, however, signaled its support through Secretary of State Marco Rubio, who stood alongside Prime Minister Benjamin Netanyahu earlier in the day.

In a report that heightened international alarm, a United Nations Commission of Inquiry accused Israel of committing genocide in Gaza, allegedly incited by senior officials including Netanyahu. Israel dismissed the findings as “scandalous” and “fake.”

Gaza’s health ministry said at least 40 people were killed in the first hours of the assault, mostly in Gaza City. Airstrikes destroyed residential towers overnight, leaving residents digging through rubble to retrieve bodies.

Abu Mohammed Hamed, whose relatives were trapped beneath collapsed buildings, told Reuters: “We don’t know how to take her out. We have been working on it since 3 a.m.”

Thousands of Palestinians streamed southward, many on foot, as Israel renewed its calls for civilians to evacuate. “They are destroying residential towers, the pillars of the city, mosques, schools, and roads,” said 70-year-old Abu Tamer, fleeing with his family. “They are wiping out our memories.”

The escalation drew sharp criticism from European allies. EU officials in Brussels said they would move to impose sanctions on Israel, including suspending trade provisions. British Foreign Secretary Yvette Cooper called the assault “reckless and appalling” and urged an immediate ceasefire. Britain and France are expected to recognize Palestinian independence later this month.

Witnesses in Tel Al-Hawa reported heavy bombardment from air, ground, and sea, with Israeli forces deploying explosive-laden robots. Some residents, unable to flee, said they had no choice but to stay. “It is like escaping from death towards death, so we are not leaving,” said Um Mohammad, a resident of Sabra.

Hamas and the IDF estimate that around 350,000 people have already fled Gaza City, with nearly twice as many remaining. Aid groups and the United Nations have denounced Israel’s tactics as mass forced displacement under conditions lacking food, medical care, and basic hygiene. Gaza’s health ministry said three more people died of starvation in the past 24 hours, bringing hunger-related deaths to at least 428. Israel maintains that reports of famine are exaggerated.

Inside Israel, some commanders have warned that the assault could jeopardize hostages still held by Hamas or create a “death trap” for soldiers. At a security meeting on Sunday, Chief of Staff Eyal Zamir urged Netanyahu to consider a ceasefire, according to officials briefed on the discussion.

Families of hostages gathered outside Netanyahu’s home in Jerusalem late Monday as the offensive intensified. “Our loved ones in Gaza are being bombarded by the IDF under the orders of the prime minister,” said Anat Angrest, whose son Matan is among the 20 hostages believed to be alive.

Information from Reuters was used in this report.