An Israeli airstrike early on Sunday night on a school in Gaza killed at least 20 people including children, according to Palestinian medical officials.
The strike on the school in Nuseirat in central Gaza was sheltering some of the many Palestinians displaced by the war.
Medics also said an Israeli strike which hit some tents of displaced Palestinians inside the Al-Aqsa Hospital in nearby Deir Al-Balah killed three people and wounded about 50 others.
It came as the Israeli military said a Hezbollah drone attack on an army base in central Israel on Sunday killed four soldiers and severely wounded seven others.
It is the deadliest strike by the terror group since Israel launched its ground invasion of Lebanon nearly two weeks ago.
The Lebanon-based Hezbollah called the attack near Binyamina city retaliation for Israeli strikes on Beirut on Thursday that killed 22 people.
It later said it targeted Israel's elite Golani brigade, launching dozens of missiles to occupy Israeli air defence systems during the assault by “squadrons” of drones.
Israel's national rescue service said the attack wounded 61. It is rare for so many people to be injured by drones or missiles fired by Hezbollah due to Israeli air defence systems.
Hezbollah's deadly strike in Israel came as the United States announced it would send a new air-defence system to Israel to help bolster protection against missiles, along with troops needed to operate it.
Israel launched its ground operation in Lebanon earlier this month with the goal of degrading Hezbollah and pushing the Iranian-backed group away from the border to allow thousands of displaced Israelis to return to their homes.
Israel is expected to strike Iran in retaliation for a missile attack earlier this month, with Iran vowing to respond to any Israeli attack.
The latest strikes came as UN peacekeeping forces in Lebanon, UNIFIL, said Israeli tanks forcibly entered the gates of one position early on Sunday and destroyed the main gate.
UNIFIL called the incident a "further flagrant violation of international law."
Israeli forces have repeatedly fired on UN peacekeepers since the start of the ground operation in Lebanon, sparking international condemnation.
Five peacekeepers have been wounded in attacks that struck their positions, with most blamed on Israeli forces.
UN Secretary-General António Guterres called the incident "deeply worrying" and said attacks against peacekeepers may constitute a war crime.
The safety of @UN personnel & property must be guaranteed.
— António Guterres (@antonioguterres) October 13, 2024
The inviolability of UN premises must be respected at all times.
Attacks against peacekeepers are in breach of international law & may constitute a war crime.
@UNIFIL_ personnel & premises must never be targeted.
Israel's military said Hezbollah operates in the peacekeepers' vicinity.
Army spokesman Lt. Col. Nadav Shoshani said that any instance of UN forces being harmed will be investigated at "the highest level."
Israeli premier Benjamin Netanyahu on Sunday called for UNIFIL to heed Israel's warnings to evacuate, accusing them of "providing a human shield" to Hezbollah.
"We regret the injury to the UNIFIL soldiers, and we are doing everything in our power to prevent this injury. But the simple and obvious way to ensure this is simply to get them out of the danger zone," he said in a video addressed to Mr Guterres, who has been banned from entering Israel.
Israel has long accused the United Nations of being biassed against it, and relations have plunged further since the start of the war in Gaza.
The war began when Hamas-led militants attacked a year ago, killing some 1,200 people, mostly civilians, and abducting around 250. Around 100 hostages are still held in Gaza, a third believed to be dead.
Israel's bombardment and its ground invasion of Gaza have killed over 42,000 Palestinians, according to Gaza's Health Ministry. Israel says it has killed over 17,000 fighters.
