At least five people have been killed and 70 injured by an Israeli strike on a hospital in Gaza, Palestinians say.
The Israeli military said it had targeted a cache of anti-tank missiles in the hospital’s “immediate vicinity”.
Overnight, more than 30 members of two Palestinian families died in Israeli strikes, Gazan health officials said.
On Monday evening Israel said seven of its soldiers had been killed in the past 24 hours, bringing the number of Israeli military dead to 25.
Two Israeli civilians have also died in the recent violence.
The Palestinian death toll from the two-week conflict has now passed 550, the majority of them civilians, according to Gaza’s health ministry. The UN says more than 100,000 Gazans have now been displaced.
Israel says it has killed more than 170 militants since Thursday night, when it launched the ground offensive phase of its two-week old operation to end rocket fire from Gaza.
Ten militants were killed on Monday after using tunnels to get into Israel near the town of Sderot.
Push for ceasefire
Palestinian television showed footage of wounded people being treated after the strike at the Al-Aqsa Hospital in Deir al-Balah in the central Gaza Strip.
Doctors say several Israeli tank shells hit the hospital’s reception, intensive care unit and operating theatres.
Most of the wounded were doctors, according to Palestinian officials.
Appeals have been made to the Red Cross to help evacuate patients from the building, the BBC’s Yolande Knell reports from Gaza.
Israel had told residents of neighbouring areas to head to Deir al-Balah for their own safety as its ground offensive continues to target neighbourhoods to the east of Gaza City for a second day, our correspondent adds.
The Israeli army said it had “successfully targeted” a cache of anti-tank missiles in the area.
“Civilian casualties are a tragic inevitability of [Hamas’] brutal and systematic exploitation of homes, hospitals and mosques in Gaza,” it said in a statement.
Israel says that approximately 131 rockets and mortars were fired at Israel on Monday, of which at least 108 hit Israel and 17 were intercepted. No casualties were reported from these attacks.
In Egypt, US Secretary of State John Kerry is holding talks with UN Secretary General Ban Ki-moon to try to arrange a ceasefire.
The UN Security Council has issued a call for an “immediate cessation of hostilities”, but did not endorse a strongly worded draft resolution backed by Arab states.
President Barack Obama said the US had “serious concerns about the rising number of Palestinian civilian deaths and the loss of Israeli lives”, and said the focus of the international community should be “to bring about a ceasefire… that can stop the deaths of innocent civilians”.
However, senior Hamas leader Ismail Haniyeh said that any ceasefire which did not address the question of the Israeli-Egyptian blockade on the territory would not be accepted.
“This siege, this unjust siege, must be lifted,” he said.
Palestinian emergency services spokesman Ashraf al-Qudra said nine members of one family were killed in overnight Israeli attacks on Rafah, on the border with Egypt.
In Khan Younis, in the south of Gaza, at least 23 members of one family died when a building was hit by an Israeli air strike, officials said.
At least 11 people were reported killed in Gaza City in a strike on a high-rise tower.
Further north, Israel continued its ground operation in the eastern fringes of Gaza City.
After moving into the densely populated area of Shejaiya neighbourhood on Sunday in search of rocket sites and tunnels, nearby areas were pounded with artillery on Monday morning.
More than 100 Palestinians and 13 Israeli soldiers lost their lives on Sunday.
Mr Ban criticised the Israeli operation in Shejaiya on Sunday as “an atrocious action”. At least 67 people were reported killed in the assault on the area, which Israel said was a “terror stronghold”.
Israel sent ground troops into Gaza after days of heavy air and naval barrages failed to stop rocket fire.
Israel says the ground operation is necessary to target Hamas’ network of tunnels, which have been used by militants to get into Israel and carry out attacks.
But the UN, Palestinians and Arab states have expressed alarm at the number of civilian casualties.