Hundreds of thousands of people are sheltering in the city and many are reluctant to follow Israel's orders to move south because of the dangers along the way, dire conditions, a lack of food in the southern area and fear of permanent displacement.
"Even if we want to leave Gaza City, is there any guarantee we would be able to come back? Will the war ever end? That's why I prefer to die here, in Sabra, my neighbourhood," Ahmed, a schoolteacher, said by phone.
At least 63 people were killed by Israeli strikes and gunfire across the Gaza Strip on Wednesday, with most of the casualties in Gaza City, local health authorities said.
They said the latest fatalities took the Palestinian death toll from the two-year war between Israel and Hamas past 65,000.
Palestinian officials and rescue workers say the true figure is likely higher as many remains are trapped under the rubble of destroyed buildings.
The war was triggered by the Hamas-led attacks on southern Israel on October 7, 2023, in which about 1200 people were killed and 251 taken hostage, according to Israeli tallies.
Gaza health authorities also reported a drone attack on a specialist children's hospital, which did not cause casualties but forced young patients and their families outside.
Israel estimates about 400,000 people, or 40 per cent of those who were in Gaza City on August 10 - when it announced plans to take control - have already fled.
The Gaza media office says 190,000 have headed south and 350,000 have moved to central and western areas of the city.
A day after Israel announced the launch of its ground offensive to seize control of the enclave's main urban centre, tanks had moved short distances towards the city's central and western areas from three directions but no major advance was reported.
An Israeli official said military operations were focused on getting civilians to head south and that fighting would intensify over the next month or two.
The official said Israel expected about 100,000 civilians to remain in the city, which would take months to capture, and the operation could be suspended if a ceasefire was reached with the Hamas militant group.
The prospects of a ceasefire appear remote after Israel attacked Hamas political leaders in Doha last week, infuriating Qatar, a co-mediator in ceasefire talks.
Defying global criticism of the attack, including a rebuke by Israel's stalwart ally the United States, Prime Minister Benjamin Netanyahu has said Israel would strike Hamas leaders anywhere.
In leaflets dropped over Gaza City, the Israeli military said Palestinians could use the newly reopened Salahudin Road to escape towards the south and that they had until lunchtime on Friday to do so.
But the situation remained chaotic and dangerous for civilians, who have been streaming away on foot, by donkey cart or in vehicles in recent days.
Much of Gaza City was laid waste early in the war in 2023 but about a million Palestinians had returned there to homes among the ruins.
Forcing them out would mean confining most of the Gaza Strip's population to overcrowded encampments in the south where a hunger crisis is unfolding.
The United Nations, aid groups and foreign governments have condemned Israel's offensive and the proposed mass displacement.
In a separate response to the conflict in general, a United Nations Commission of Inquiry concluded on Tuesday that Israel had committed genocide in the Gaza Strip.
Israel called the assessment "scandalous" and "fake".
