Iran struck Israel early Saturday with barrages of missiles after a massive onslaught targeted the Islamic republic's nuclear and military facilities and killed several top generals.

Air-raid sirens and explosions rang out across Israel overnight, with its military calling on residents to take refuge in bomb shelters Saturday morning.

The Israeli military said dozens of missiles – some intercepted – had been fired in the latest salvos from Iran. Smoke billowed above skyscrapers in downtown Tel Aviv, an AFP journalist reported, as Iran's Revolutionary Guard said it had attacked dozens of targets in Israel.

Israel's firefighting service said its teams were responding to the aftermath of Iranian missile strikes, including working to rescue people trapped in a high-rise building.

Rescuers said 34 people had been wounded in the Gush Dan area, including a woman who later died of her injuries, according to Israeli media reports.

Resident Chen Gabizon told AFP he ran to an underground shelter after receiving an alert notification.

"After a few minutes, we just heard a very big explosion, everything was shaking, smoke, dust, everything was all over the place," he said.

In Iran's capital Tehran early Saturday, fire and heavy smoke billowed from Mehrabad airport, an AFP journalist said, as local media reported a blast in the area.

Iran said earlier it had activated its air-defense system and explosions could be heard across the capital.