The Israeli military warned Iranians living near nuclear reactors to evacuate, while Prime Minister Benjamin Netanyahu said the attacks by Israel so far were nothing compared with what Iran would see in the coming days.

The Iranian and Israeli strikes mark the most sustained, direct attacks ever between the two rivals. Three people were killed in Israel and at least 78 in Iran, officials said.

Blasts rang out across a swath of the Middle Eastern republic’s territory, targeting its nuclear capabilities, military leadership and scientists.

Israel and Iran launched fresh attacks on each other overnight into Sunday, stoking fears of a wider conflict after Israel expanded its surprise campaign against its main rival with a strike on the world's biggest gas field.

Iran launched dozens of ballistic missiles toward Israel on Friday night in retaliation for Israel's surprise attack early Friday. Israel struck at the heart of the Iran's nuclear program, killing several nuclear scientists as well as high-ranking military leaders, according to Israeli officials.

Israel’s attack on Iran was long in the making – the result of years of meticulous planning by Israel and days of high-stakes talks between Tel Aviv and Washington, officials told CNN.

Israel has warned of more attacks on Iran after Tehran fired waves of missiles and drones that killed three people and wounded dozens in Israel.

Separately in the city’s south, Shahr Rey, one of the country’s largest oil refineries, was also struck, according to Iranian state news media. Emergency crews were trying to contain the fire, and a resident of Tehran, Reza Salehi, said he could see the flames from miles away.

Israel’s unprecedented attacks on Iran had at their core an elusive and high-risk goal: eradicating the country’s controversial nuclear program.

Israeli Prime Minister Benjamin Netanyahu is on the mission of his lifetime. For years, the veteran leader has made the destruction of Iran’s nuclear program his top priority.

A series of loud explosions are heard in central Israel as the military says it carried out intelligence-based strikes in Tehran.