Israeli fighter jets hit targets in Gaza on Friday shortly after a weeklong truce expired, the military said, as the war resumed in full force.

Air strikes hit the south of the besieged enclave, including the community of Abasan east of the town of Khan Younis, Gaza’s interior ministry said. Another air raid hit a home northwest of Gaza City.

Loud, continuous explosions were heard coming from across the Strip and black smoke billowed from the territory.

In Israel, sirens blared at three communal farms near Gaza, warning of incoming rocket fire and suggesting that Hamas had also resumed its attacks.

The Israeli military’s announcement of the renewed strikes came only 30 minutes after the temporary pause, which began on November 24, expired at 7am (05:00 GMT) on Friday.

At least 21 Palestinians were killed across Gaza in the first two hours after Israel’s army resumed its attacks, Gaza’s health ministry said.

This included two people killed in Beit Lahia in northern Gaza; seven in Maghazi in central Gaza; one in Khan Younis; two in Hamad town; and nine in Rafah, all in the southern Gaza Strip.

Most of Gaza’s population of 2.3 million is now crammed into the south with no exit after Israel instructed hundreds of thousands to evacuate the north during its initial bombardment. This raises questions over how an Israeli offensive in southern Gaza can avoid heavy civilian casualties.

Since Israel’s war on Gaza began on October 7, at least 15,000 Palestinians, including more than 6,000 children, have been killed.