GAZA, Sept. 17 (Xinhua) -- Smoke choked the skies over Gaza City on Wednesday as Israeli tanks, under the cover of a relentless artillery and air barrage, pushed deeper into the city in one of the largest ground operations since the conflict began.

The advance was preceded by a stark warning. In the morning, Israeli leaflets fluttered down, urging civilians to flee south and declaring the city a "violent fighting zone."

An evacuation route was announced, but for thousands of terrified residents, the question was where to go and how to get there alive.

"We thought the western part of Gaza City would be safe, but the bombardment has followed us everywhere," said Mahmoud al-Zard, a 45-year-old father of five. "There is no safe place anymore."

Al-Zard's family had already been displaced once when their home in the Shuja'iyya neighborhood was destroyed. Now, forced from the tent where they had taken refuge, they were fleeing again.

"We only took a few belongings and some water," he said. "We live in constant fear. Every shell brings the tanks closer. It feels like dying a thousand times a day."

On the streets, a desperate exodus was underway. Al-Rimal, usually one of the enclave's busiest commercial districts, was a ghost town of shattered facades and rubble. Families piled into cars, trucks, and donkey-drawn carts, a chaotic procession set to the soundtrack of ambulance sirens.

The very act of fleeing has become a life-or-death gamble. On Wednesday, medical sources said an Israeli drone strike hit a vehicle carrying a displaced family near the entrance of Al-Shifa hospital, killing at least 13 people.

This followed a similar attack a day earlier that left five dead after their car burst into flames. Paramedics reported that the relentless strikes made it nearly impossible to reach bombed sites.

"We often find entire families buried under rubble," said Mohammed Samih, an emergency responder. "Every minute of delay can cost lives."

Gaza's health authorities reported on Wednesday that at least 98 people had been killed by Israeli fire in the past 24 hours, bringing their tally for the conflict to 65,062 dead and 165,697 injured.

Israeli Defense Minister Israel Katz on Tuesday delivered a grim ultimatum: "If Hamas does not release the hostages and disarm itself, Gaza will be destroyed and will become a tombstone." Hamas, in turn, condemned the offensive as "a new chapter in the war of genocide and systematic ethnic cleansing."

Meanwhile, the city's hospitals were buckling under the strain. At Al-Shifa Hospital, Gaza's largest medical facility, doctors were overwhelmed. Dozens of wounded arrived within hours, many of them victims of artillery strikes. Medical staff worked with dwindling electricity, fuel, and essential supplies.

Munir al-Bursh, the director-general of Gaza's health authorities, warned that the entire system was on the verge of collapse.

"The images from Gaza tell the story: bodies under rubble, children haunted by hunger and fear, hospitals collapsing on their staff and patients," he said, calling the situation "a moral and legal test for the world."