Eleven teenagers and young adults have been killed and 19 injured after an attack which hit a football pitch in the Israeli-occupied Golan Heights, according to Israeli emergency services and military spokespeople.

The Israel Defense Forces (IDF) said a rocket fell on the Majdal Shams area of the territory.

The strike was the deadliest in the area since cross-border exchanges between Israel’s military and Hezbollah escalated after Hezbollah fired rockets at Israeli positions a day after the outbreak of the Israel-Gaza war in October.

The IDF blamed Hezbollah for the attack but Hezbollah spokesman Mohamad Afif denied “any relation to the Majdal Shams incident”.

“All accusations [of the group’s involvement] are false”.

But before the reports of the strike’s impact emerged, Hezbollah had claimed responsibility for four attacks, including one on the military headquarters of the Hermon Brigade, on the slopes of Mt Hermon. The base is around two miles from the football pitch where the explosion occurred.

The strikes followed an Israeli attack in Lebanon that killed four militants.

Israeli Prime Minister Benjamin Netanyahu, who has been visiting the US, has brought forward his return home. He was briefed by aides on Saturday.

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.”

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 Druze people live.

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 on the Golan can still study and work in Israel, though only those with citizenship can vote and are required to serve in the army.

The vast majority of the international community does not recognise Israel’s annexation of the area.

The Druze are part of an Arabic-speaking ethnic group based in Lebanon, Syria and northern Israel. In Israel, they have full citizenship rights and comprise about 1.5% of the population.