Iran's Revolutionary Guards said the missile attack under way against Israel was in response to the killing of Hezbollah chief Sayyed Hassan Nasrallah last week as well as that of the Hamas leader.
"In response to the martyrdom of (Hamas leader) Ismail Haniyeh, Hassan Nasrallah and (Guards commander) Nilforoshan, we targeted the heart of the occupied territories (Israel)," the Guards said in a statement reported by the Fars news agency.
Iran's Guards threatened to carry out "crushing attacks" on Israel if it retaliated.
"If the Zionist regime reacts to Iranian operations, it will face crushing attacks," the Islamic Revolutionary Guard Corps said in a statement carried by Iranian news agency Fars.
A series of explosions were heard in Tel Aviv and near Jerusalem. The explosions near Jerusalem were so loud that windows shook.
Residents were ordered to shelter in place and remain close to bomb shelters. The order was sent to mobile phones and announced on national television. TV stations reported sirens in parts of Jerusalem as well as central Israel.
"Iran's attack is continuing. You are requested to remain in a protected space until further notice. The explosions you are hearing are from interceptions or fallen projectiles," the Israeli army said in a statement to Israelis.
- Biden orders US military to shoot down Iranian missiles targeting Israel -
President Joe Biden ordered the U.S. military on Tuesday to "aid Israel's defense" and shoot down Iranian missiles targeting Israel, the White House said.
Biden and Vice President Kamala Harris, the Democratic nominee in next month's U.S. presidential election, are both monitoring Iran's attack on Israel from the White House situation room, it said in a statement.