The death toll in Gaza now exceeds 10,000 after nearly one month of Israeli bombardment, the Hamas-run health ministry said Monday as the offensive against the Palestinian militant group showed signs of intensifying.
Israeli Prime Minister Benjamin Netanyahu has vowed no letup despite mounting international calls for a ceasefire.
Hundreds of overnight strikes pushed the death toll to 10,022, mostly women and children, a spokesman for the health ministry told a press conference on Monday afternoon.
Two paediatric hospitals and Gaza's only psychiatric hospital were hit, the ministry said, after the director of another hospital, the Deir al-Balah in central Gaza, reported he had counted 58 dead.
"These are massacres! They destroyed three houses over the heads of their inhabitants -- women and children," one resident, Mahmud Meshmesh, told AFP.
"We have already taken 40 bodies out of the rubble," he said as crowds prayed around corpses wrapped in white shrouds.
The Israeli military accuses Hamas of building tunnels underneath hospitals, schools and places of worship in Gaza to hide fighters, store arms and ammunition, and plan attacks -- charges the militant group has denied.
Ground forces with tanks have flooded the northern half of the Gaza Strip and tightened an encirclement of Gaza City, effectively splitting the territory in two, even as hundreds of thousands of civilians remained in the north despite Israeli evacuation orders.
Israel's ally the United States sent its top diplomat Antony Blinken on a whirlwind Middle East tour that wrapped up on Monday in Turkey, where again his host pressed for an Israeli ceasefire, which Washington has declined to endorse.
The heads of major United Nations agencies issued a joint statement also calling for a ceasefire inside the territory of 2.4 million people where an Israeli siege has cut off most water, food and fuel supplies.
"For almost a month, the world has been watching the unfolding situation in Israel and the Occupied Palestinian Territory in shock and horror at the spiralling numbers of lives lost and torn apart," said the statement.
"We need an immediate humanitarian ceasefire. It's been 30 days. Enough is enough. This must stop now."
The Israeli army said on Monday it had pounded Gaza with "significant" new strikes on 450 targets, having earlier said it had already hit over 12,000. It also reported seizing a Hamas command post in central Gaza, where tanks were driving between the ruins of buildings.
"We will take the fight to Hamas wherever they are -- underground, above ground," Israeli army spokesman Jonathan Conricus said, referring to Hamas tunnels, and repeating calls for civilians to leave the urban war zone.
"We will be able to dismantle Hamas, stronghold after stronghold, battalion after battalion, until we achieve the ultimate goal, which is to rid the Gaza Strip -- the entire Gaza Strip -- of Hamas."
Israeli troops and Hamas fighters have engaged in fierce house-to-house combat in densely populated north Gaza, where the war has sent 1.5 million people fleeing to other parts of the territory.
Netanyahu has remained firm on his position, vowing on Sunday that "there won't be a ceasefire until the hostages are returned".
Shortly before the latest barrage of strikes, internet and telephone lines were cut, the army said.
Israel has air-dropped leaflets and sent text messages ordering Palestinian civilians in northern Gaza to head south, but a US official said Saturday at least 350,000 civilians remained in the worst-hit areas.
The Rafah crossing between the Gaza Strip and Egypt reopened Monday to allow the evacuation of foreigners and dual nationals, the Hamas government said, ending a two-day closure prompted by a dispute over the passage of ambulances.
Six ambulances carrying wounded Gazans also arrived in Egypt on Monday as the evacuations resumed, a border official said.
Blinken on his regional tour -- which took him to Israel, Jordan, the occupied West Bank, Cyprus, Iraq and Turkey -- called for "humanitarian pauses" while rejecting Arab countries' demands for a ceasefire.
After meeting his Turkish counterpart Hakan Fidan in Ankara on Monday, Blinken said Washington was working "very aggressively" to dramatically expand aid reaching trapped civilians in Gaza, but he did not provide details before boarding a flight to Japan.
Turkish President Recep Tayyip Erdogan himself was travelling across his country's remote northeast on Monday, apparently snubbing Blinken.
NATO member Turkey, which is allied to the Palestinians but also has ties with Israel, has said it is recalling its ambassador to Israel and breaking off contacts with Netanyahu.
Meeting with Blinken in the West Bank on Sunday, Palestinian Authority president Mahmud Abbas denounced "the genocide and destruction suffered by our Palestinian people in Gaza at the hands of Israel's war machine".
The war has exacerbated tensions in the West Bank, where more than 150 Palestinians have been killed in clashes with Israeli forces and settlers since it started, according to the Palestinian health ministry.
In Israeli-annexed east Jerusalem, a female Israeli soldier was "seriously" wounded in a knife attack before "border police forces neutralised the terrorist by shooting", police said.
The Israeli military said Monday it had arrested Palestinian activist Ahed Tamimi, 22, in a raid in her West Bank town of Nabi Salih on suspicion of "inciting violence and terrorist activities".
Tamimi became prominent at age 14 when she was filmed biting an Israeli soldier to prevent him from arresting her younger brother, and for later slapping another Israeli soldier.
A large portrait of her was painted on the Israeli separation wall with the West Bank.
When AFP asked about the reasons for her arrest, a security source forwarded an Instagram post, which has circulated widely and is attributed to the young activist.
According to the post, written in Arabic and Hebrew, she called for the massacre of Israelis in explicitly violent terms, referring to Hitler.
Her mother, Narimane Tamimi, denied that she wrote the post and added that "when Ahed tries to open a social media account, it's immediately blocked".