JERUSALEM/DUBAI (Reuters) – Iran launched a swarm of explosive drones and fired missiles at Israel late on Saturday in its first ever direct attack on Israeli territory, risking a major escalation as the United States pledged “ironclad” backing for Israel.

Sirens wailed and Reuters journalists in Israel said they heard distant heavy thuds and bangs from what local media called aerial interceptions of explosive drones. The ambulance service said a 10-year-old boy was critically injured.

Israel’s military said more than 100 drones were launched from Iran, with security sources in Iraq and Jordan reporting dozens seen flying overhead and US officials saying the US military had shot some down.

Israel’s Channel 12 TV cited an unnamed Israeli official as saying there would be a “significant response” to the attack.

Iran’s state news agency cited a source saying its military had also launched a wave of ballistic missiles. Israel’s military also said missiles were fired, but there was no immediate report of these striking in Israel.

Iran has vowed retaliation for what it called an Israeli strike on its Damascus consulate on April 1 that killed seven Guards officers including two senior commanders and said its strike was a punishment for “Israeli crimes”. Israel has neither confirmed nor denied responsibility for the consulate attack.

“Should the Israeli regime make another mistake, Iran’s response will be considerably more severe,” the Iranian mission to the United Nations said, warning the U.S. to “stay away”. However, it also said Iran now “deemed the matter concluded”.

US President Joe Biden, who on Friday had warned Iran against an attack, cut short a visit to his home state of Delaware to meet national security advisers in the White House Situation Room, an official said. He pledged to stand with Israel.