"The world welcomed the New Year with celebrations and festivities, while we witnessed 2025 begin with the first Israeli massacre in the town of Jabalia just after midnight," civil defence agency spokesman Mahmud Bassal told AFP.

"Fifteen people were martyred and more than 20 were injured" in the strike on a house where displaced people were living, he said.

The Israeli military, when contacted, said it was looking into the reported strike.

Since October 6, the military has been conducting a major land and air offensive in northern Gaza, particularly targeting Jabalia and its adjacent refugee camp.

The military says it is an effort to prevent Hamas militants from regrouping there and it has killed hundreds of fighters, while rescuers in the area say thousands of civilians have died.

On Monday United Nations rights experts said the "siege" appears to be part of an effort "to permanently displace the local population as a precursor to Gaza's annexation".

Bassal said those living in the house were members of the Badra, Abu Warda, and Taroush families who had sought refuge there.

Nearly all of Gaza's 2.4 million people have been displaced at least once since the start of the war on October 7 last year.

The dead and injured from the strike in Jabalia were moved to Al-Mamadani hospital, said rescuer Mohammed, who provided only his first name.

"They were pulled out from beneath the rubble of the targeted house," he said.

A relative said rescuers were still searching for any survivors.

"The house has turned into a pile of debris," said Jibri Abu Warda, adding that the strike occurred at around 1:00 am (2300 GMT Tuesday).

He said the explosions shook the area, and rescuers reached the targeted house only in the morning.

"It was a massacre, with body parts of children and women scattered everywhere. They were sleeping when the house was bombed," Abu Warda said.

"No one knows why they targeted the house. They were all civilians."

- Fear of cold, missiles -

The military assault, which began on October 6, has since expanded across northern areas of the Palestinian territory and last week targeted a major hospital which is now empty of its staff and patients.

On Friday, the military raided Kamal Adwan Hospital in Beit Lahia, describing it as "one of the largest" operations targeting militants since the start of the war.

The raid and arrest of the hospital's director have drawn global attention to Gaza's broken health care system.

The military said it killed more than 20 militants and detained over 240 others, including the director of the hospital, whom it described as a suspected Hamas militant.

The World Health Organization, Amnesty International and others have called for the immediate release of the director, Hossam Abu Safiyeh, 51, a paedeatrician.

Israel's military has regularly accused Hamas of using hospitals as command centres, which the militants deny.

A report published Tuesday by the United Nations Human Rights Office said "insufficient information" has been made available to substantiate "vague" Israeli accusations of military use of hospitals.

A separate Israeli strike on Wednesday targeted a group of people in the Al-Manara neighbourhood of Khan Yunis, in Gaza's south, killing at least four people, civil defence said.

Several displaced Gazans said they were facing not just Israeli bombardments but also falling temperatures and heavy rains, which have flooded thousands of tents across the territory.

"For three days, we haven't slept out of fear that our children would fall sick because of the winter, as well as fear of missiles falling on us," said Samah Darabieh, a woman displaced from central Gaza's Deir el-Balah and now living in Beit Lahia.

"Two days ago, they bombed Al-Wafaa hospital, which is behind us, and the shrapnel dropped here."

The Hamas-run territory's health ministry said seven children have died from the cold within the span of a week.

The war in Gaza began when Hamas attacked Israel on October 7 last year, which resulted in the deaths of 1,208 people, mostly civilians, according to an AFP tally based on official Israeli figures.

Israel's retaliatory response has killed at least 45,553 people in Gaza, the majority civilians, according to Gaza's health ministry, figures which the United Nations considers reliable.