Twelve children and young adults have been killed and dozens injured after a rocket hit a football pitch they were playing on in the Israeli-occupied Golan Heights, Israeli authorities say.

The Israel Defense Forces (IDF) said a rocket fired by the powerful Lebanese militant group Hezbollah fell on the Druze town of Majdal Shams - a claim denied by the group.

Israeli Prime Minister Benjamin Netanyahu vowed retaliation against Hezbollah, saying the group would "pay a heavy price."

The incident has the potential to trigger an all-out war between Israel and Hezbollah, whose forces have regularly exchanged fire since the outbreak of the Israel-Gaza war in October.

Saturday's attack was the deadliest loss of life on Israel's northern border since the war began on 7 October.

Hezbollah spokesman Mohamad Afif denied responsibility for the attack, and the BBC is trying to verify reports that the militant group told the United Nations that the explosion was caused by an Israeli interceptor rocket.

Israeli authorities said all of those killed were between the ages of 10 and 20.

Verified video shows crowds of people on a football pitch and stretchers being rushed to waiting ambulances.

Majdal Shams is one of four villages in the Golan Heights, where about 25,000 members of the Arabic-speaking Druze religious and ethnic group live.

Before reports of the strike's impact emerged, Hezbollah had claimed responsibility for four other attacks.

One was on the military headquarters of the Hermon Brigade, on the slopes of Mt Hermon, which lies on the border between Israel and Lebanon. The base is around 3km (2 miles) from the football pitch.

IDF spokesman Daniel Hagari, who visited the scene of the attack, accused Hezbollah of "lying and denying responsibility for the incident."

He said that the rocket was an Iranian-made Falaq-1 "owned exclusively by Hezbollah."

"Our intelligence is clear. Hezbollah is responsible for the murder of innocent children," he said, adding that Israel was preparing to retaliate.

Although Israel and Hezbollah regularly trade fire and have both suffered casualties, since October, both sides have refrained from actions which could escalate into a broader war in southern Lebanon.

Israeli Prime Minister Benjamin Netanyahu, who was on a visit to the US, is returning home early.

In an angry statement, Sheikh Mowafaq Tarif, the leader of the Druze community in Israel, said the "horrific massacre" had crossed "every possible red line".

"A proper state cannot allow continuous harm to its citizens and residents. This has been the ongoing reality in the northern communities for the past nine months," he added.

Foreign Minister Israel Katz told Israel's Channel 12 news: “We are facing an all-out war.”

Israeli President Isaac Herzog called the incident a "terrible and shocking disaster" and said that "the state of Israel will firmly defend its citizens and its sovereignty".

Lebanon's government also issued a rare statement in response, saying it "condemns all acts of violence and aggression against all civilians and calls 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," the statement added.

The US and EU have also condemned the attack.

Most Druze live in northern Israel, Lebanon and Syria. In Israel, they have full citizenship rights and comprise about 1.5% of the population.

They were offered Israeli citizenship when the Golan Heights was annexed from Syria in 1981, but only a minority accepted.

Most have retained an allegiance to Syria. Druze in the Golan can still study and work in Israel, though only those with citizenship can vote and Druze men are required to serve in the army.

The Druze are the largest non-Jewish group to serve in the IDF.

The vast majority of the international community does not recognise Israel's annexation of the Golan Heights. (BBC)

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