Israel's operation against Hamas saw one of its bloodiest days on Saturday, with 46 Palestinians killed in Gaza and two Israeli soldiers dying in a clash with militants who infiltrated the Jewish state.
As Israeli warplanes bombarded Gaza from the air, and ground troops pressed an assault on land, the Palestinian death toll rose to 342, with rights groups warning that a growing number of victims are children.
UN chief Ban Ki-moon was Saturday headed for the region to bolster intense diplomatic efforts aimed at ending 12 days of bloodshed in and around Gaza, even as Israel warned it was ready to intensify its ground assault aimed at destroying a network of cross-border tunnels.
Despite the blistering offensive, Palestinian commandos in central Gaza managed to use one of the tunnels to infiltrate southern Israel, sparking a deadly skirmish in which one militant and two soldiers were killed, the army said.
The soldiers died when the militants fired a machinegun and an anti-tank missile at an army patrol, the army said.
Troops fired back, killing one of them, while the others fled back through the tunnel in an operation claimed by Hamas's military wing, the Ezzedine Al-Qassam Brigades, which said 12 militants had been involved.
Also Saturday, an Israeli Bedouin was killed when a rocket hit his encampment in southern Israel in an attack which also wounded four of his family, among them two young children, police said.
The deaths raised to five the total number of Israelis killed since July 8 -- three soldiers and two civilians -- in the deadliest confrontation between Israel and Hamas militants since 2009.
Israel's Chief-of-Staff, Lieutenant General Benny Gantz, said the army was "expanding the ground phase of the operation", warning there would be "moments of hardship", alluding to the possibility of further Israeli casualties.
In a separate incident late on Friday, militants strapped explosives on to a donkey in another attempt to attack troops.
But soldiers spotted the donkey approaching them "suspiciously" and fired at it, causing it to explode, a statement said.
In Gaza, after a relative lull on Friday, violence picked up again, with intensifying tank shelling and air strikes killing 46 people on Saturday.
So far 342 Palestinians have been killed since Israel on July 8 launched Operation Protective Edge aimed at halting cross-border rocket fire from Gaza.
Among Saturday's dead were two six-year-olds and a toddler, emergency services spokesman Ashraf al-Qudra said.
The increasing number of children killed in the conflict is causing a growing outcry, with a joint statement from the NGOs War Child and Defence for Children International saying more children had been killed than militants.
Figures provided by the UN children's agency, UNICEF, indicate 73 of the victims were under the age of 18.
"Children should be protected from the violence, and they should not be the victims of a conflict for which they have no responsibility," UNICEF's Catherine Weibel told AFP.
The UN agency for Palestinian refugees UNRWA has opened 44 of its schools to shelter those fleeing in the most heavily-bombarded areas.
So far, more than 50,000 Gazans have sought sanctuary at UN institutions, the agency said.
Ban was leaving for the Middle East on Saturday to help Israelis and Palestinians "end the violence and find a way forward", the agency said.
In Amman, French Foreign Minister Laurent Fabius said brokering a ceasefire must be the "absolute priority," urging all parties an Egyptian-led effort.
"This initiative has been widely supported by the international community and Arab countries," he said at a news conference in the Jordanian capital.
"So now we need to ensure that the party that has rejected it accepts the plan to avoid losing more human lives," he added.
An Egyptian-led truce effort collapsed earlier this week after Israel accepted it but Hamas militants continued to fire rockets over the border.
In northern Israel, the growing violence brought angry protestors onto the streets, with 1,500 Arab Israelis demonstrating in Kafr Kana against Israel's military operation, police said.
Protests against the Israeli offensive have also sprung up across the world, with thousands joining a pro-Palestinian rally in London, chanting "Israel is a terror state", while demonstrators in Paris clashed with riot police after their own protest was banned.
And in restive India-administered Kashmir, police shot dead a teenager during another protest against Israel's operation in Gaza, officials said.