Washington DC - The White House said Sunday that rocket fire that killed 12 young people in the Israeli-annexed Golan Heights was "conducted by Lebanese Hezbollah."

Calling the attack "horrific," National Security Council Spokeswoman Adrienne Watson said in a statement that "it was their rocket, and launched from an area they control. It should be universally condemned."

The Israeli military has said the youths were struck on Saturday by an Iranian-made rocket carrying a 110-pound warhead that Lebanon's Iran-backed Hezbollah group fired at a football field in the Druze Arab town of Majdal Shams.

"Our support for Israel's security is ironclad and unwavering against all Iran-backed threats, including Hezbollah," Watson said.

"We have been in continuous discussions with Israeli and Lebanese counterparts since the horrific attack," she added.

Vice President Kamala Harris, the presumptive Democratic presidential nominee, also condemned the attack in language similar to that used by the White House.

Harris "has been briefed and is closely monitoring Hezbollah's horrific attack on a soccer field in Majdal Shams," her NSC advisor Phil Gordon wrote on X.

"She condemns this horrific attack and mourns for all those killed and wounded."

Hezbollah has said it had no connection to the incident.

The group has described its past cross-border fire as an act of support for Palestinian Islamists from Hamas, who have been fighting Israel's military in Gaza since October 7, when they attacked southern Israel.