Iran and Israel launched tit-for-tat strikes on Friday night and the early hours of Saturday.
Israel launched what it called a "pre-emptive" strike early on Friday, hitting nuclear and military sites inside Iran.
Red alerts were issued throughout Israel, with the military saying that Iran had launched a round of missiles.
“The defence systems are working to intercept the threat,” the military said in a post on social media. “You must enter the protected areas and remain there until further notice.”
Explosions were reported in Tel Aviv as missiles hit. The military said "dozens" of missiles had been launched against areas across the country and some were intercepted.
Earlier, buildings burned following an attack that killed one person, according to local media, and left at least 34 injured.
Israel's military said less than 100 missiles were launched at the country. Most were intercepted by air defence systems or failed to reach their targets, the military said.
Army spokesman Brig Gen Effie Defrin said buildings had been hit.
“Further interceptions may occur, and we are taking action to eliminate this threat,” he said. Israel's fire service said it was dealing with “several major incidents” mainly in the Tel Aviv area as a result of Iranian missile fire.
The wave of strikes came after Israel began its latest attack on Iran.
About an hour earlier, air defences were activated as the strikes targeted Tehran, according to state media and local residents.
A resident of Tehran sent The National a video in which the sound of explosions could be heard along with lights in the night sky.
“It is a huge wave,” said the resident, who was unable to identify what sites in the city were being attacked.
Some of the weapons were intercepted by air defences, while others hit, the resident added.
The Fars and Irna news agencies said air defences were activated in response to a missile and drone attack on the Iranian capital.
Iran's ambassador to the UN said 78 people, many of them civilians, had been killed in the strikes so far.
Earlier, in a televised speech, Iran's supreme leader Ayatollah Ali Khamenei promised that “the Islamic Republic will prevail over the Zionist regime”.
“Don’t think that they [Israel] hit and it’s over. No. They started the work and started the war. We will not allow them to escape safely from this great crime they committed,” Mr Khamenei said.
“A big error, a mistake, and the consequences of it will make it miserable, God willing. Our armed forces are ready, and the country's officials and all members of the public are behind the armed forces.”
