The Israel Defense Forces confirmed Tuesday that it had launched a controversial  and long-expected major ground offensive in Gaza City, as local medics said dozens were killed and injured in strikes, and the desperate Israeli families of hostages held in Gaza said they were “terrified” for their loved ones.

The IDF said that it had “begun destroying Hamas infrastructure in Gaza City,” confirming the start of a major military push in the area after heavy bombing overnight.

The start of the operation was also confirmed by Prime Minister Benjamin Netanyahu, who said that Israel “has begun an intensive operation in Gaza City.”

The premier made the statement at the start of a session in his corruption trial, as he requested to be excused from his regularly scheduled testimony due to the “important things happening.”

In a warning to Palestinian civilians, the military said that Gaza City was “considered a dangerous combat zone,” and once again instructed residents to evacuate the area immediately — as it had repeatedly done in recent days — and head for an Israeli-designated humanitarian zone in the Strip’s south, cautioning that they would be “at risk” if they remained in place.

According to the IDF statement, more than 40 percent of the city’s estimated one million residents have “left the city for their safety and the safety of their loved ones.”

IDF estimates from Monday night indicated that more than 350,000 Palestinians had evacuated Gaza City. But that contradicted a UN estimate issued earlier in the day that said around 220,000 Palestinians had fled northern Gaza over the past month.

Thousands were estimated to have left the city overnight amid a heavy wave of airstrikes, an Israeli defense source said.

The source said that the rate of Palestinian civilians leaving Gaza City would likely increase as the IDF’s ground offensive to conquer the city progresses.

Last week, the IDF ordered Palestinians in all areas of Gaza City to evacuate immediately ahead the offensive. However, moving can be costly, and space is at a premium in the overcrowded south of the Strip. Many had said they would not leave, exhausted from repeated displacement over the course of the 23-month-old war.

Overnight, a large wave of airstrikes was carried out in Gaza City, as two divisions began to advance into new areas beyond those previously under Israeli control.

Witnesses told of relentless bombing of  the city, some areas of which were already in ruins after nearly two years of Israeli strikes after the Hamas-led onslaught on October 7, 2023, triggered the war.

“The danger keeps increasing,” witness Ahmed Ghazal said, adding that homes had been destroyed and residents were trapped under the rubble.

“We can hear their screams,” the 25-year-old said.

Hospitals in Gaza City said that between midnight and 10:30 a.m. on Tuesday, 39 people were killed as a result of IDF strikes in the city. The highest number was reported at Shifa Hospital, where officials said 23 people were declared dead.

The figures could not be independently verified. Health and rescue services in the Gaza Strip are tied to Hamas, and the numbers do not differentiate between civilians and fighters.

“A very tough night in Gaza,” Dr. Mohamed Abu Salmiya, director of Shifa Hospital, told The Associated Press.

“The bombing did not stop for a single moment,” said Abu Salmiya, who was arrested by IDF troops in November on suspicion of having allowed Hamas to use the Gaza City hospital as a center of operations, but was later released by security services due to a lack of prison space, in a contentious move.

“There are still bodies under the rubble,” he said.

Videos circulating on social media showed families spending the night in the streets of Gaza City following the heavy Israeli strikes overnight.

The bombing was so intense that at times it could be heard in Tel Aviv (70 kilometers, or 44 miles, from Gaza City) and other areas of central Israel.

Defense Minister Israel Katz said Tuesday that troops were “fighting valiantly to create the conditions for the release of the hostages and the defeat of Hamas.”

“Gaza [City] is burning. The IDF is striking the terror infrastructure with an iron fist,” Katz said in a statement. “We will not relent and we will not back down, until the mission is completed.”

In addition to the strikes, Palestinian media reported that the Israeli military detonated several explosive-laden remote-controlled armored personnel carriers in the Gaza City neighborhoods of Tel al-Hawa and Rimal on Tuesday morning.

During the war, the IDF has repurposed decommissioned M113 APCs by packing them with explosives and attaching remote-control capabilities, in order to drive them into areas with Hamas infrastructure without risking the lives of troops.

The massive blasts from the APCs are used to destroy Hamas infrastructure, including booby trapped areas.

The early stages of the offensive, dubbed “Gideon’s Chariots B,” began several weeks ago with increased strikes on Hamas targets, including high-rise towers, and ground operations on the outskirts of Gaza City and in several neighborhoods in the east of the city.

The military said that the 162nd and 98th divisions were expanding their operations in Gaza City, and in the coming days, a third division, the 36th, would join, adding tens of thousands more soldiers to the offensive.

In the coming days and weeks, ground troops were set to push deeper into the city and encircle it as part of efforts to defeat Hamas’s forces there, according to the IDF.

The military has estimated that there are thousands of Hamas fighters in Gaza City, as well as some 600,000 civilians who have not yet evacuated.

Additionally, a number of hostages abducted from Israel are believed to be held in the city.

The military said IDF Chief of Staff Lt. Gen. Eyal Zamir — who has said that he would keep the hostages and troops at the forefront of his mind during the operation, and has repeatedly urged ministers to agree to a ceasefire and hostage release deal — was commanding the offensive personally from Southern Command HQ.

Some 60,000 reservists have been called up for the operation, in addition to another 70,000 already in reserves service. Despite reports of burnout, the IDF asserted that the reservist turnout rate was high, at 75%-85% in most units.

The reservists included three brigades and several more battalions, and many combat support soldiers, including in intelligence and logistics.

Not all of the reservists are participating in the operation to capture Gaza City, as some are instead replacing standing army troops on other fronts.

In addition to the Gaza City offensive, the IDF said the 99th Division was conducting defensive operations in Israel’s buffer zone in northern Gaza, while the Gaza Division was operating in the Strip’s south.

Meanwhile, US Secretary of State Marco Rubio warned that there was a small window of opportunity for a ceasefire deal, and said that he would ask Doha to stay on as a mediator as he visited the Gulf ally, a week after Israeli airstrikes tried and failed to eliminate Hamas leaders in the emirate.

Rubio was pessimistic about the chances of a ceasefire deal but said Qatar was in a unique position to help.

“We’re going to ask Qatar to continue to do what they’ve done, and we appreciate very much, and that is, play a constructive role in trying to bring this to an end,” Rubio told reporters as he flew out of Ben Gurion Airport to Doha after meetings with Netanyahu and other top officials.

“Obviously they have to decide if they want to do that after last week or not, but we want them to know that if there’s any country in the world that could help end this through a negotiation, it’s Qatar,” he said.

Rubio also said that there was short period of time for a potential hostage-ceasefire deal to be reached.

“The Israelis have begun to take operations there,” Rubio said. “So we think we have a very short window of time in which a deal can happen. We don’t have months anymore, and we probably have days and maybe a few weeks to go.”

Rubio, who met Monday in Jerusalem with families of hostages in Gaza, acknowledged that Hamas had leverage by holding them.

“If there were no hostages and no civilians in the way, this war would have ended a year and a half ago,” he said.

The group representing the vast majority of hostages’ families, The Hostages and Missing Families Forum, said they were “terrified” for their loved ones with the start of the operation.

“[Netanyahu] is doing everything to ensure there is no deal and not to bring them back,” the Forum charged in a statement.

Overnight and into Tuesday, families of hostages still held in Gaza gathered outside Netanyahu’s residence, pleading with him to stop the Gaza City operation.

Some pitched tents and slept outside his home in protest.

“I have one interest — for this country to wake up and bring back my child along with 47 other hostages, both living and deceased, and to bring our soldiers home,” Einav Zangauker, whose son Matan is being held in Gaza, shouted outside Netanyahu’s residence.

“If he… sends our precious, brave, heroic soldiers to fight while our hostages are being used as human shields — he is not a worthy prime minister,” said Zangauker.

Times of Israel staff and Lazar Berman contributed to this report.