Israeli tanks and troops pressed towards Gaza City on Thursday but met fierce resistance from Hamas militants using mortars and hit-and-run attacks from tunnels as the Palestinian death toll from nearly four weeks of bombardments mounted.

At the southern end of the besieged enclave, foreign passport-holders were being allowed out through the Rafah crossing into Egypt.

The war is closing in on the Gaza Strip’s main population centre in the north, where the Islamist group is based and where Israel has been telling people to leave as it vows to annihilate Hamas once and for all.

“We are at the gates of Gaza City,” Israeli military commander Brigadier General Itzik Cohen said.

Fighters of Hamas and its ally Islamic Jihad were emerging from tunnels to fire at tanks, then disappearing back into the network, residents said and videos from both groups showed, in guerrilla-style operations against a far more powerful army.

“They never stopped bombing Gaza City all night, the house never stopped shaking,” said one man living there, asking not to be identified by name. “But in the morning we discover the Israeli forces are still outside the city, in the outskirts and that means the resistance is heavier than they expected.”

Israeli officers have stressed the difficulties of fighting in an urban environment. The strategy appears for now to concentrate large forces in the northern Gaza Strip rather than launch a ground assault on the entire territory.

The latest war in the decades-old conflict began when Hamas fighters broke through the border on Oct. 7. Israel says they killed 1,400 people, mostly civilians, and took more than 200 hostages in the deadliest day of its 75-year history.

Israel’s ensuing bombardment of the small Palestinian enclave of 2.3 million people has killed at least 8,796 people, including 3,648 children, according to Gaza health authorities.

Though Western nations and the United States in particular have traditionally supported Israel, harrowing images of bodies in the rubble and hellish conditions inside Gaza have triggered appeals for restraint and street protests around the world.

Israel’s right-wing Prime Minister Benjamin Netanyahu knows, however, that his career and legacy depend on crushing Hamas.

‘Hamas has prepared well’

Residents reported mortar fire throughout the night in areas around Gaza City and said Israeli tanks and bulldozers were sometimes driving over rubble and knocking down structures rather than using regular roads as planes bombed from overhead.

Brigadier General Iddo Mizrahi, chief of Israel’s military engineers, told Army Radio troops were in a first stage of opening access routes in Gaza. “This is certainly terrain that is more heavily sown than in the past with minefields and booby-traps,” he said. “Hamas has learned and prepared itself well.”

After a total blockade of Gaza for more than three weeks, foreign passport-holders and some severely wounded people were being allowed out. Palestinian border official Wael Abu Mehsen said 400 foreign citizens would leave for Egypt via the Rafah crossing on Thursday, after at least 320 on Wednesday.

Another 60 critically injured Palestinians would be crossing too, Mehsen added.

Israel’s latest strikes have included the heavily-populated area of Jabalia that was set up as a refugee camp in 1948.

Gaza’s Hamas-run media office said at least 195 Palestinians were killed in the two hits on Tuesday and Wednesday, with 120 missing and at least 777 people hurt.

“It is a massacre,” said one person on the scene as people desperately hunted for trapped victims.

Israel, which accuses Hamas of hiding behind civilians, said it killed two Hamas military leaders in Jabalia.

With Arab nations increasingly vocal in their outrage at Israel’s actions, the U.N. High Commissioner for Human Rights also expressed concern that Israel’s “disproportionate attacks...could amount to war crimes”.

The Israeli military said on Thursday another soldier had died in the Gaza fighting, bringing to 17 the number killed since ground operations were expanded on Friday.

Troops had killed “dozens of terrorists”, it added.

Violence has also spread to the occupied West Bank, with Israeli military raids to arrest suspected militants touching off confrontations with gunmen and people throwing stones.

Palestinian medics said three teenagers were killed there by Israeli army fire early on Thursday. Israeli military spokespeople had no immediate comment.

Separately, the military and medics said Palestinian gunmen killed an Israeli motorist in the West Bank. There was no immediate claim for that from Palestinian factions.

‘We open our eyes on dead people’

As international calls for a “humanitarian pause” in hostilities go unheeded, conditions are atrocious in Gaza, with food, fuel, drinking water and medicine all running short.

“We open our eyes on dead people and we close our eyes on dead people,” said Dr Fathi Abu al-Hassan, a US passport holder waiting to cross into Egypt on Wednesday.

Hospitals, including Gaza’s only cancer hospital, are struggling due to fuel shortages. Israel has refused to let humanitarian convoys bring in fuel, citing concern that Hamas fighters would divert it for military use.

Ashraf Al-Qudra, a spokesperson for the Gaza health ministry, said the main power generator at the Indonesian Hospital was no longer functioning.

The hospital was switching to a back-up generator but would no longer be able to power mortuary refrigerators and oxygen generators. “If we don’t get fuel in the next few days, we will inevitably reach a disaster,” he said.

US Secretary of State Antony Blinken was due to depart on Thursday for his third visit to Israel in less than a month.

He plans to meet Netanyahu on Friday to voice solidarity with its close ally but also to reassert the need to minimize Palestinian civilian casualties, his spokesperson said.

Blinken will also stop in Jordan, one of a handful of Arab states to have normalised relations with Israel. On Wednesday, though, Jordan withdrew its ambassador from Tel Aviv in protest at the assault on Gaza.