An Israeli airstrike flattened a home on Thursday in an area of southern Gaza that the military had declared a safe zone, as Israeli troops continued their assault in the nearby city of Khan Younis.

Palestinian hospital officials said the blast killed at least 12 people, almost all of them children.

Israel’s offensive has focused on Khan Younis, where the military said on Thursday it has uncovered tunnels used by Hamas and was fighting members of the militant group that attacked southern Israel on October 7.

Israel has vowed to continue its campaign in Gaza until Hamas is destroyed. An apparent Israeli strike that killed a top Hamas leader in Beirut has stirred fresh fears that the conflict could expand into other parts of the region.

The killing of Sameh Arouri prompted warnings of retaliation from Hamas’ ally, the Lebanese Hezbollah militia.

But there was no immediate escalation in the daily exchanges of rocket fire and shells between Hezbollah and the Israeli military over the two countries’ border.

After nearly three months, Israel’s bombardment and ground assault have killed more than 22,400 people in Gaza, more than two-thirds of them women and children, according to the Health Ministry in the Hamas-run territory.

The ministry count does not differentiate between civilians and combatants.

The campaign has driven more than 85% of Gaza’s 2.3 million people from their homes. Israel’s assault levelled much of northern Gaza, and ground assaults in the south have pushed most of the population into smaller slivers of the territory.

With strikes continuing throughout Gaza, Palestinians say nowhere is safe.

On Thursday, an air strike hit a house in Mawasi, a small rural strip on Gaza’s southern coastline where Israel’s military has said Palestinians should flee to escape the combat zone.

The blast killed a man and his wife, seven of their children and three other children ranging in age from five to 14, according to a list of the dead who arrived at Nasser Hospital in Khan Younis.

There was no immediate response from Israel’s military.

Israeli troops pushed into Khan Younis in early December and have been fighting Hamas militants there for weeks. The military said on Thursday that its troops uncovered a large tunnel hundreds of metres long with an entrance in a field next to a mosque.

Footage released by the military showed it blasting into rubble buildings where fighters who reportedly fired on troops had hidden or that held Hamas infrastructure. Military officials did not elaborate.

Israel blames Hamas for the high civilian death toll, saying it operates within residential areas and has an extensive tunnel network beneath civilian sites.

Defence Minister Yoav Gallant said Israel is seeking a “clear victory” over Hamas, which has ruled the territory since 2007.

The October 7 attack from Gaza into southern Israel killed about 1,200 people, and some 240 others were taken hostage.