Israeli warplanes struck Houthi sites in Yemen’s capital and elsewhere in the country following an increase in missile attacks by the Iran-backed militia, including one overnight that damaged a school near Tel Aviv.

The Israeli strikes killed nine people, according to reports from a Houthi-affiliated television station, and damaged energy facilities and power stations.

Houthi-run Al Masirah Television reported that seven people were killed in Israel’s strikes on Al-Salif port close to Hodeida, while two died at the nearby Ras Isa oil terminal.

The Houthis said they targeted Tel Aviv with two ballistic missiles early on Thursday. Israel said part of a missile warhead hit a school in the Tel Aviv suburb of Ramat Gan, following an interception attempt. There were no reports of casualties, despite the damage. It’s unclear what happened to the second projectile, but the Israeli army said it was investigating reports of damage in other areas.

Millions of Israelis were forced into bomb shelters as air sirens went off across large parts of the country.

An Israeli military spokesman said jets were already flying toward Yemen when the Houthis fired their missiles. Israel, he said, had planned its operation — complicated by Yemen lying about 1,700 kilometers (1,060 miles) away — for some time.

The Houthis have been firing drones and missiles at Israel regularly, saying they’ll continue until there’s a ceasefire with Hamas in Gaza. The projectiles have mostly been intercepted before reaching Israeli territory, but in July a Houthi drone killed a man in Tel Aviv.

Israel reacted to that attack by striking Houthi targets for the first time, and did so again in September. The latest mission was the first time Israel has targeted Sanaa, the Yemeni capital.

In the past two weeks, a Houthi drone hit an apartment block in the south of Israel and on Sunday a long-range missile was fired at the center of the country.

The Houthis have continued their attacks on Israel and on ships in the Red Sea despite the strikes by Israel and several others by the U.S. and U.K. air forces.

The group’s maritime assaults have effectively closed the southern Red Sea and parts of the Gulf of Aden to most Western shipping firms, pushing up global freight prices.

Hamas and the Houthis are designated as terrorist groups by the U.S. and many other governments. The Yemeni group captured Sanaa and other areas, including the strategic port of Hodeida, soon after Yemen’s civil war began in 2014. It is funded and advised by Iran and a key member of Tehran’s “axis of resistance” against Western and Israeli interests.

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