A rocket strike on a football field killed at least 11 children and teenagers, Israeli authorities said.
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.
Israel blamed the Lebanese militant group Hezbollah for the strike in the Israeli-controlled Golan Heights, but Hezbollah rushed to deny any role.
Israel’s military called it a “very serious” event and said it would act accordingly.
“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.
He called it the deadliest attack on Israeli civilians since the Hamas attack on October 7 that sparked the war in Gaza.
Hezbollah chief spokesman Mohammed Afif told The Associated Press that the group “categorically denies carrying out an attack on Majdal Shams”.
It is unusual for Hezbollah to deny an attack.
The militant group said 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.
It said it was in response to Israeli airstrikes on villages in southern Lebanon.
The strike followed earlier cross-border violence on Saturday, when Hezbollah said three of its fighters were killed, without specifying where.
Israel’s military said its air force targeted a Hezbollah arms depot on the border village of Kfar Kila, adding that militants were inside at the time.
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.
Video showed paramedics rushing stretchers off the soccer field toward waiting ambulances.
Ha’il Mahmoud, a resident of Majdal Shams, told Channel 12 that children were playing football when the rocket hit the field.
He said a siren was heard seconds before the rocket hit, but there was no time to take shelter.
The office of Israeli Prime Minister Benjamin Netanyahu, who was on a visit to the United States, said he would cut short his trip by several hours, without specifying when he would return.
Lebanon’s government in a statement, without mentioning Majdal Shams, urged “immediate cessation of hostilities on all fronts” and condemned all attacks on civilians.
Israel and Hezbollah have been trading fire since October 8, a day after Hamas militants stormed into southern Israel.
In recent weeks, the exchange of fire along the Lebanon-Israel border has intensified, with Israeli airstrikes and rocket and drone attacks by Hezbollah striking deeper and farther away from the border.
Saturday’s violence comes as Israel and Hamas are weighing a ceasefire proposal that would wind down the nearly 10-month war and free the roughly 110 hostages who remain captive in Gaza.
Hamas’ surprise attack on October 7 killed some 1,200 people and took 250 others hostage.
Israel launched an offensive that has killed more than 39,000 people, according to local health authorities.
Since early October, Israeli airstrikes in Lebanon have killed more than 450 people, mostly Hezbollah members, but also around 90 civilians and non-combatants.
On the Israeli side, 44 have been killed, at least 21 of them soldiers.