UNIFIL spokesperson Andrea Tenenti told Al Jazeera Arabic that the peacekeeping force was “more concerned than ever about the possibility of the conflict expanding in southern Lebanon” following the attack on Majdal Shams.

Tenenti added his team was communicating with actors on both sides of the border to reduce tensions at the Blue Line, which divides Lebanon from Israel and the Golan Heights.

At least 12 people have been killed and 18 others wounded in a rocket attack on a football pitch in the town of the Majdal Shams in the Israeli-occupied Golan Heights on Saturday, Israeli authorities confirmed.

Israel’s military spokesman Daniel Hagari said children were among those killed and accused the Lebanese group Hezbollah of carrying out the attack on Saturday.

Hezbollah swiftly denied responsibility for the attack. The group announced in a statement it “categorically denies the allegations reported by certain enemy media and various media platforms concerning the targeting of Majdal Shams”.

“The Islamic Resistance has no connection to this incident,” it added, referring to its military wing.

Hezbollah has been exchanging fire with Israeli forces in areas near the Israel-Lebanon border since October 8, when Tel Aviv launched its war on the Gaza Strip.

The cross-border attacks, which Hezbollah said it launched in solidarity with the Palestinian people amid Israel’s war on Gaza, have led to fears of a larger regional conflagration.

Israel’s Prime Minister Benjamin Netanyahu’s office announced he would fly home early from his trip to the United States, where he met several senior US officials.

Netanyahu told the leader of the Druze community in Israel, “Hezbollah will pay a heavy price, the kind it has thus far not paid,” during a phone call, according to a statement from his office.

Lebanon’s government, in a statement, urged the “immediate cessation of hostilities on all fronts” and condemned attacks on civilians.

At least 10 people have been killed and 20 wounded in the attack on Majdal Shams, Israeli army spokesperson Daniel Hagari said on Saturday.

The military has issued a statement on its official Telegram channel claiming that according to a “situational and the intelligence in our possession, the rocket launch toward Majdal Shams was carried out by” Hezbollah.

The military added that the rocket attack hit a football pitch in the Israeli-occupied Golan Heights, “which caused multiple civilian casualties, including children”.

Earlier, the Israeli army claimed that a barrage of 30 rockets were fired from Lebanon at northern Israel.

A senior official from Lebanon’s group, Mohammad Afif, has told Reuters that Hezbollah was not responsible for the attack.

Following the attack, Prime Minister Benjamin Netanyahu held security consultations with his military secretary, Roman Gofman. The office of the prime minister added in a statement on X that Netanyahu will later hold a security situation assessment with the heads of the defence establishment.

Immediately after he was informed of the strike on Majdal Shams, Netanyahu gave instructions for his flight back to Tel Aviv from Washington to depart as early as possible, according to his office.

Israeli officials signal the military response to the attack will likely be a very aggressive one.

Channel 12 cites a senior Israeli official in the prime minister’s delegation to Washington as saying: “The events in the north will bring about a dramatic turn in fighting in the area.”

Kan news sites an unnamed senior official as saying, “The disaster at Majdal Shams could signal a change of direction in the war.”

A security source tells Kan: “This is an incident that we will not gloss over. There will be a severe response.”

Walla news also reports the IDF is preparing for harsh retaliation.

Hezbollah started launching rockets at Israel on October 8, saying it will continue until there is a ceasefire in the Gaza Strip.

The military tensions between Israel and Hezbollah have killed nearly 350 Hezbollah fighters in Lebanon and more than 100 civilians, including medics, children and journalists, while in Israel, 20 Israeli civilians, a foreign agricultural worker and 20 Israeli soldiers have been killed.