At least 11 teenagers and young adults were killed after a rocket exploded on a football pitch in the Israeli-occupied Golan Heights, emergency services reported.
Verified footage showed crowds of people on a football pitch and stretchers being rushed to waiting ambulances as a further 19 people were injured in the attack.
Footage aired on Israeli Channel 12 showed a large blast in one of the valleys in the Druze town of Majdal Shams, in the Golan Heights, which Israel captured from Syria in the 1967 Mideast war and annexed in 1981.
Israel quickly blamed the attack on Hezbollah, an Iran-backed militia based in southern Lebanon, but the group has denied responsibility. The group usually takes responsibility for its strikes on Israeli soil.
It is the deadliest strike on an Israeli target along the country’s northern border since the fighting between Israel and Hezbollah erupted, and risked unleashing a broader regional war.
The militant group previously claimed its fighters carried out nine different attacks using rockets and explosive drones against Israeli military posts, the last of which targeted the army command of the Haramoun Brigade in Maaleh Golani with Katyusha rockets.
Hezbollah, allied with Hamas, another Iran-backed militia in control of the Gaza Strip, has been fighting Israel in solidarity with the Gaza-based group since they killed around 1,200 Israeli citizens on 7 October and took 251 more as hostages. Around half of those hostages still remain in Gaza.
The Israeli military said the latest rocket fell on the Majdal Shams area of the Golan Heights territory.
“Hezbollah fired a rocket at children playing soccer in northern Israel. It then lied and claimed they did not carry out the attack,” said the military’s chief spokesman, Rear Admiral Daniel Hagari.
Hezbollah spokesman Mohamad Afif earlier denied “any relation to the Majdal Shams incident”.
“All accusations [of the group’s involvement] are false,” he added.
Israeli prime minister Benjamin Netanyahu, who has been visiting the US, will head back to Israel early to be briefed on events, while the country’s top diplomat, Israel Katz, told a local tv channel that they are now “facing an all out war”.
Lebanon’s government, a separate entity from Hezbollah, also issued a rare statement in response to the attack.
It said it “condemns all acts of violence and aggression against all civilians and call for an immediate cessation of hostilities on all fronts”.
“Targeting civilians is a flagrant violation of international law and goes against the principles of humanity,” it added.
It comes as Israeli airstrikes hit a school in Gaza where dozens of displaced people were taking shelter with at least 30 people pronounced dead, according to the Gaza health ministry.
Eight women and 15 children are among those killed after a strike hit a girls’ school in Deir Al-Balah, with those injured taken to Al Aqsa Hospital. People have been seen searching the rubble for further victims, with more than 100 wounded.
Israel’s military said that it had targeted a Hamas command and control centre which was being used to store weapons and plan attacks. A statement added that it had warned civilians before the strike.
Majdal Shams is one of four villages in the Golan Heights, where about 25,000 Druze people live.
Most refused Israeli citizenship when it was offered to them after Israel annexed the region from Syria in 1981. Many have since retained an allegiance to Syria, though around 1.5 per cent of the population have acquired full citizenship rights.
Druze on the Golan can still study and work in Israel, though only those with citizenship can vote and serve in the army.
The vast majority of the international community does not recognise Israel’s annexation of the area.
The Israeli Druze community is the only major non-Jewish group in the country whose members are required to serve in the Israeli military.