JERUSALEM (AFP) — Hundreds of thousands of people sought shelter from Hezbollah rockets fired from Lebanon into northern Israel on Sunday, the military said, as a United Nations (UN) official warned of imminent regional “catastrophe” from the worsening violence.

The Israeli army said more than 100 projectiles had been fired from Lebanon early on Sunday.

“Hundreds of thousands of people had to take refuge in bomb shelters” across northern Israel, military spokesperson Lieutenant Colonel Nadav Shoshani told Agence France-Presse.

Israel’s rescue service said at least four people suffered “shrapnel injuries,” three near the city of Haifa.

Israel’s civil defense agency ordered all schools in the country’s north closed following the rocket fire.

Hezbollah said it had targeted Israeli military production facilities and an air base in the Haifa area in response to the communication device blasts on Tuesday and Wednesday that killed 39 and wounded almost 3,000.

Israel’s military said it launched strikes on Hezbollah targets in southern Lebanon in response to the rocket fire and, Shoshani said, “to prevent a larger-scale attack.”

Israel has signalled its intention to turn its focus to Iran-backed Hezbollah after nearly a year of cross-border fire that began with the outbreak of the war between Israel and Palestinian Hamas militants in the Gaza Strip.

Further exchanges of fire came after military spokesperson Rear Admiral Daniel Hagari late Saturday said dozens of Israeli warplanes were “widely” striking Hezbollah targets in southern Lebanon.

Meanwhile, an Iraqi coalition of pro-Iran armed groups claimed on Sunday a drone attack against Israel, where the military said it had intercepted “multiple suspicious aerial targets” coming from Iraq overnight.

“The fighters of the Islamic Resistance of Iraq targeted on Sunday morning a strategic location in the occupied territories using drones,” the Iraqi coalition said in a statement on Telegram, referring to Israel, and adding it was carried out “in support of our people in Gaza.”

The attack caused no injuries, according to the Israeli military. An Israeli air strike on Friday killed the head of Hezbollah’s elite unit Ibrahim Aqil, whose funeral in Beirut on Sunday is expected to draw large crowds.

“With the region on the brink of an imminent catastrophe, it cannot be overstated enough: there is NO military solution that will make either side safer,” UN special coordinator for Lebanon Jeanine Hennis-Plasschaert said on social media platform X.