The Israeli military said three rockets targeted its territory from the Gaza Strip, the latest in a flurry of launches by militants in the devastated Palestinian territory.
"Friday was a harsh day for the residents of Gaza, particularly in Gaza City, due to the continual Israeli bombardment," civil defence spokesman Mahmud Bassal told AFP.
He said several children were among the dead.
Seven people were killed in an Israeli strike in the Shujaiya neighbourhood of Gaza City, Bassal said.
Gaza resident Mohammed Abu Labda, whose brother was among those killed, said for Israel it was an "act of revenge".
"They've destroyed everything that moves on this earth, even the trees, so what about people? This is a war of extermination," he told AFP.
The Israeli military said that over the previous 24 hours, "the Israeli air force struck approximately 40 Hamas terrorist gathering points".
Some of the targets "were embedded in areas that previously served as schools", it charged.
Bassal denied the allegation. He accused the military of "preventing food and drinking water from reaching dozens of medical staff, patients and wounded" at the Indonesian Hospital in the northern town of Beit Lahia.
He said the hospital had been sending out distress calls since Thursday, adding that it was now "just a pile of rubble and walls. There's no hospital."
The military told AFP it had not struck the Indonesian Hospital over the past day nor damaged any essential equipment.
It said "there is no need to evacuate the hospital", adding that it was coordinating with hospital officials about delivering humanitarian assistance.
'Nothing but rubble'
On Sunday, a United Nations team visited the Indonesian Hospital.
"Around me there's nothing but rubble and destruction," UN aid official Jonathan Whittall said in a video released after the visit.
Israel's military has repeatedly accused Hamas of using hospitals as command centres, an allegation the militants deny.
A report published by the UN human rights office on Tuesday said "insufficient information" has been made available to substantiate "vague" Israeli accusations of military use of hospitals.
As violence raged in the Gaza Strip, Hamas said indirect negotiations with Israel were to resume in Qatar later Friday for a truce and hostage release deal.
The militant group, whose October 7, 2023 attack on Israel triggered the Gaza war, said the talks would "focus on ensuring the agreement leads to a complete cessation of hostilities (and) the withdrawal of occupation forces".
Mediators Qatar, Egypt and the United States have been engaged in months of back-and-forth talks between Israel and Hamas that have failed to end nearly 15 months of war.
A key obstacle to a deal has been Israel's reluctance to agree to a lasting ceasefire.
On Thursday, Prime Minister Benjamin Netanyahu's office said he had authorised Israeli negotiators to continue talks in Doha.
Militants, meanwhile, fired three rockets from Gaza towards Israel, the military said.
Such launches have become far rarer than earlier in the war but have intensified since late December as Israel presses on with a three-month offensive in the north of the territory.
Attacks from Yemen
The Israeli army has kept up an intensive bombardment of north Gaza since October 6, saying it is an effort to prevent Hamas militants from regrouping.
UN human rights experts said on Monday that the north Gaza "siege" appears to be part of an effort "to permanently displace the local population as a precursor to Gaza's annexation".
Bassal estimated that 10,000 people remained in the northern towns of Jabalia, Beit Lahia and Beit Hanoun, down from between 150,000 and 200,000 before the war.
Hamas's 2023 attack on Israel resulted in the deaths of 1,208 people, mostly civilians, according to an AFP tally based on Israeli official figures.
Israel's retaliatory military campaign has killed at least 45,658 people in Gaza, the majority of them civilians, according to figures from the Hamas-run territory's health ministry which the United Nations considers reliable.
The Israeli military said it had also shot down a missile and a drone fired from Yemen, where Iran-backed rebels have stepped up their campaign against Israel since Lebanese militant group Hezbollah agreed to a November ceasefire.
Israel has carried out retaliatory strikes against rebel targets in Yemen, including the airport of the rebel-held capital Sanaa late last month.
