Israeli rocket alarms have sounded in the south of Israel, the Dead Sea, the greater Jerusalem area and the north of the country, amid a large-scale drone and missile attack by Iran on Saturday night.
Iran launched hundreds of drones and missiles targeting Israel in response to a suspected Israeli attack on an Iranian compound in Syria earlier this month which killed two brigadier generals and five other members of Iran's powerful Islamic Revolutionary Guards (IRGC).
Residents in some areas reported hearing numerous explosions. Many missiles were intercepted by Israel's missile defence system, according to media reports.
British air force jets were among those being used to shoot down Iranian drones, the Press Association reported.
Aircraft in Iraq and Syria have been deployed to intercept "any airborne attacks within range of our existing missions," the Ministry of Defence said.
Several US media reported that US forces had also intercepted drones aimed at Israel.
Israel's Magen David Adom rescue service said a 10-year-old girl was seriously injured in the attack, although it was not clear whether this was from a direct hit or shrapnel.
She was a Bedouin from the area around the city of Arad in the Negev Desert, the rescue service said.
Some kind of military retaliation by Iran to the strike on the embassy compound had been widely expected after repeated threats from Tehran.
On Saturday night, the IRGC said the attack was in "response to the recent crimes of the Zionist regime."
"The wicked regime will be punished," said Iranian leader Ayatollah Ali Khamenei in a social media post on the platform X, formerly Twitter.
Israeli Prime Minister Benjamin Netanyahu wrote that "Israel is strong" in a post on X, just as the Israeli army first confirmed the Iranian drone and missile attack late on Saturday.
"The State of Israel is strong, the IDF [Israel Defense Forces] are strong, the people of Israel are strong," Netanyahu wrote on X, just four minutes before an army post saying that Iran had launched drones.
In an accompanying video message he said: "We have a clear principle: whoever attacks us, we will attack them."
Iran's mission to the United Nations warned Israel against a renewed counter-attack.
"Iran’s military action was in response to the Zionist regime’s aggression against our diplomatic premises in Damascus. The matter can be deemed concluded," it posted on X.
If the Israeli regime takes another such step, Iran's response will be "considerably more severe," the mission said.
Israel has been Iran's declared arch-enemy since the Islamic Revolution of 1979.
The decades-old tensions between the two countries have escalated following the outbreak of the Gaza war in October.
The tensions have also played out on the border with Lebanon, where Israel and the Iran-backed Hezbollah movement have exchanged fire on an almost daily basis since tensions rose in the wake of the war in Gaza, with deaths and injuries on both sides.
Hezbollah said on Saturday night it had fired at Israeli barracks in the area with Katyusha rockets.
Israel shut its airspace in response to the massive Iranian attack, Israeli media reported, citing the aviation authority. Jordan, Iraq and Lebanon had also closed their airspace, according government officials and local media. Egyptian airspace remained open for the time being.
IDF spokesman Daniel Hagari described the attack as "a severe and dangerous escalation."
He added that Israel's defensive and offensive capabilities are at the "highest level of readiness ahead of this large-scale attack from Iran."
Israeli Defence Minister Yoav Gallant said earlier that the nation was prepared.
"In recent days we have strengthened our defensive and offensive array and we are determined to take any measures required to defend the citizens of the State of Israel," he said, according to his office.
US President Joe Biden was being kept informed of the situation and was to meet with his security team at the White House for talks, a spokeswoman for the National Security Council said.
The US has been Israel's staunchest ally and biggest military supporter.
"Our commitment to Israel’s security against threats from Iran and its proxies is ironclad," Biden posted on X after meeting his national security team.
Top EU officials as well as British Prime Minister Rishi Sunak condemned the Iranian strike.
Sunak said Britain will “continue to stand up for Israel’s security and that of all our regional partners, including Jordan and Iraq.” The UK and its allies were "urgently working to stabilize the situation," he said.
The German ambassador to Israel, Steffen Seibert, urged all Germans on the ground in Israel to follow the instructions of the security authorities, describing it as "a direct attack like never before."
Earlier, the IRGC navy detained a container ship in the Gulf that is allegedly linked to Israel, news reports said on Saturday.
Images distributed by the Iranian state news agency IRNA and Tasnim news agency, which is considered a mouthpiece of the IRGC, showed commandos rappelling from a military helicopter onto the ship's deck.